Optical imaging and measurement systems and methods for cataract surgery and treatment planning

ABSTRACT

An optical measurement system and apparatus for carrying out cataract diagnostics in an eye of a patient includes a Corneal Topography Subsystem, a wavefront aberrometer subsystem, and an eye structure imaging subsystem, wherein the subsystems have a shared optical axis, and each subsystem is operatively coupled to the others via a controller. The eye structure imaging subsystem is preferably a fourierdomain optical coherence tomographer, and more preferably, a swept source OCT.

RELATED APPLICATIONS

This application is a non-provisional application and claims the benefitunder 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No.62/197,539, filed Jul. 27, 2015, which is incorporated herein in itsentirety by reference.

BACKGROUND

Cataract extraction is a frequently performed surgical procedure. Acataract forms through opacification of the eye's crystalline lens. Thecataract scatters light passing through the lens, and may perceptiblydegrade vision. Generally, a cataract can vary in degree from slight tocomplete opacity. Early in the development of an age-related cataract,the power of the lens may increase, causing near-sightedness (myopia).Over time, the gradual yellowing and opacification of the lens mayreduce the perception of blue colors as shorter wavelengths are morestrongly absorbed and scattered within the cataractous crystalline lens.As the cataract formation gradually progresses, the patient mayexperience progressive vision loss.

Cataract treatment may involve surgically removing the opaquecrystalline lens, and replacing it with an artificial intraocular lens(IOL). Each year, an estimated 15 million cataract surgeries areperformed worldwide. Cataract surgery can be performed using a techniquecalled phacoemulsification in which an ultrasonic tip with associatedirrigation and aspiration ports is used to sculpt the relatively hardnucleus of the lens to facilitate removal through an opening made in theanterior lens capsule. The nucleus of the crystalline lens is containedwithin an outer membrane of the lens referred to as the lens capsule. Toaccess the lens nucleus, surgeons first perform a manual continuouscurvilinear capsulohexis (CCC) procedure to form a circular hole in theanterior side of the lens capsule. Alternatively, surgeons may use alaser surgical system to perform the anterior capsulotomy to gain accessto the lens nucleus. The surgical laser beam may also be used tofragment the cataractous crystalline lens before it is aspirated out ofthe eye. After the cataractous lens is removed, a synthetic foldableintraocular lens (IOL) can be inserted into the remaining lens capsuleof the eye.

Planning a cataract treatment can be challenging. There is significantvariation between patients in many important eye biometric parameters,each of which may affect surgical planning, treatment, and outcome.Moreover, many patients may have biometric configurations, including forexample, corneal lower order and higher order aberrations, extreme axiallengths, and/or previous conical refractive treatments such as LASIK,which may also affect surgical planning, treatment, and outcome. Forexample, with respect to eye aberrations, some patients havenear-sightedness (myopia), far-sightedness (hyperopia), or astigmatism.Near-sightedness occurs when light focuses in front of the retina, whilefar-sightedness occurs when light refracts to a focus behind the retina.Astigmatism occurs when the corneal curvature is unequal in two or moredirections. Various surgical methods have been developed and used totreat these types of aberrations. Ideally, for best results and outcome,a cataract surgeon would have access to not only ocular biometryinformation, but also to information on the eye's anterior cornealsurface, posterior conical surface, anterior lens surface, posteriorlens surface, lens tilt, lens thickness, and lens position in order toplan cataract treatment pre-operatively, and/or to assess thepost-operative refractive state of a patient's eye with the implantedIOL.

A variety of optical diagnostic systems have been developed, each ofwhich provides a limited subset of the desired measurements. Thus,currently most patients have various measurements performed on differentdevices if the measurements are taken at all. There is a significantdisadvantage, however, to using multiple measurement devices in cataractplanning because the patient's eye may be in different positions duringeach of the measurements, and/or it may have changed between thedifferent measurements, or the measurement may have been made underdifferent conditions. Further, there may be no way to combine or fusethe data sets from different devices to obtain a single,three-dimensional model of the patient's eye. Hence, it can be oftendifficult to apply advanced vision modeling techniques, such as raytracing, because the current diagnostic environment is often inadequateto reliably produce the three-dimensional models necessary for accuratevision modeling.

As a result, there is an ongoing need for an improved optical imaging,measurement, and diagnostic system that can obtain most, if not all, ofthe necessary biometric and structural features of a patient's eye withthe patient's eye in a single orientation within a brief period of time,that can fuse the data obtained from various optical techniques toachieve an accurate three-dimensional model of a patient's eye, and thatcan utilize advanced vision modeling techniques, such as ray tracing orother power calculation techniques, to improve cataract planning andoutcome evaluation.

SUMMARY OF THE INVENTION

This disclosure provides embodiments for improved optical measurementsystems and methods for carrying out imaging and measurements used fordiagnostics, treatment planning, and IOL placement for cataracttreatment and surgery.

An eye imaging and measurement system for planning a cataract treatmentin a patient's eye according to one embodiment comprises: a CornealTopography Subsystem, a wavefront aberrometer subsystem, and an eyestructure imaging subsystem, wherein the subsystems have a sharedoptical axis, and each subsystem is operatively coupled to the othersvia a controller. The eye structure imaging subsystem is selected fromthe group consisting of an optical coherence tomographer (OCT), aScheimpflug imager, a fluorescence imager, a structured lighting imager,a wavefront tomographer, and an ultrasound imager. The eye structureimaging subsystem is an optical coherence tomographer, including forinstance, a Fourier domain optical coherence tomographer, a spectraldomain optical coherence tomographer, or a swept source opticalcoherence tomographer.

In many embodiments, the eye imaging and measurement system comprises aniris imaging subsystem operatively coupled to the controller.

In many embodiments, the eye imaging and measurement system comprises aposterior corneal astigmatism imaging and measurement subsystemoperatively coupled to the controller.

In many embodiments, the eye imaging and measurement device comprises afixation target subsystem operatively coupled to the controller. Thistarget allows for fixating the eye during on axis measurements. In otherembodiments, this target can be used to perform off-axis measurements atdifferent eccentricities.

In many embodiments, the controller is coupled to an Optical CoherenceTomography (OCT) subsystem configured to sequentially scan the eye in aplurality of OCT scan patterns, each scan pattern being at a differentaxial depth of a patient's eye. The plurality of scan patterns comprisean anterior segment OCT scan pattern at or near a location of a cornea,a lenticular OCT scan pattern at or near a location of a lens, and aretinal OCT scan patter at or near a location of a retina. The pluralityof imaging scan patterns preferably comprises an anterior segment OCTscan pattern suitable to measure a plurality of an anterior cornealsurface, a corneal pachymetry, a central corneal thickness, and ananterior chamber depth of a patient's eye. The plurality of imaging scanpatterns preferably also comprises a lenticular OCT scan segment scanpattern suitable to measure a plurality of a lens thickness, an anteriorlens surface, a posterior lens surface, and a lens surface tilt anddecentration. The plurality of imaging scan patterns comprises a retinalOCT segment scan pattern suitable to measure at least one of an axiallength and a retinal layer thickness information. These measurements mayalso be done post-operatively, allowing the measurement of IOL axialposition, tilt, and decentration, so that the instrument allows forevaluation of postoperative outcomes and secondary treatment planning,if needed.

In many embodiments, the eye imaging and measurement system comprises amemory operable to store data acquired from each of the CornealTopography Subsystem, the wavefront sensor subsystem, and the OpticalCoherence Tomography subsystem, wherein the stored data includes aplurality of ocular biometry information, anterior corneal surfaceinformation, posterior corneal surface information, anterior lenssurface information, and posterior lens surface information, lens tiltinformation, and lens position information. The ocular biometryinformation preferably comprises a plurality of a central cornealthickness (CCT), an anterior chamber depth (ACD), a pupil diameter (PD),a white to white distance (WTW), a lens thickness (LT), an axial length(AXL), and retinal layer thickness.

In many embodiments, the eye imaging and measurement system furthercomprises a memory operable to store Intraocular Lens (“IOL”) Data, theIOL data including a plurality of dioptic power, anterior and posteriorradius, IOL thickness, refractive index and dispersion, asphericity,toricity, echelette features, haptic angulation, and lens filter.

In many embodiments, the eye imaging and measurement system furthercomprises a memory operable to store intraocular lens (“IOL”) model datafor a plurality of IOL models, IOL model having associated with aplurality of predetermined parameters selected from the group consistingof dioptic power, anterior and posterior radius, IOL thickness,refractive index, asphericity, toricity, echelette features, hapticangulation, and lens filter.

An improved system for selecting an intraocular lens (IOL) forimplantation, comprises: a memory operable to store data acquired fromeach of the Corneal Topography Subsystem, the wavefront sensorsubsystem, and the Optical Coherence Tomography subsystem, wherein thestored data includes a plurality of ocular biometry information,anterior corneal surface information, posterior corneal surfaceinformation, anterior lens surface information, posterior lens surfaceinformation, lens tilt information, and lens position information; thememory further operable to store intraocular lens (“IOL”) model data fora plurality of IOL models, the IOL model having associated with it aplurality of predetermined parameters selected from the group consistingof dioptic power, anterior and posterior radius, IOL thickness,refractive index, asphericity, toricity, echelette features, hapticangulation, and lens filter; and a processor coupled to the memory, theprocessor deriving the treatment of the eye of the patient applying, foreach of the plurality of identified IOL models, to: (1) predict aposition of one of the identified IOL models when implanted in thesubject eye, based on the plurality of characteristics; (2) simulate thesubject eye by means of ray tracing for a plurality of IOL predeterminedparameters and the predicted IOL position; (3) based on that, select anIOL spherical equivalent (SE) and cylinder (C) power, as well asdetermine the optimum IOL orientation based on said eye model; (4)propose the selected IOL power for one or more IOL models from theplurality of IOLs corresponding to the optimized IOL(s) based onpredetermined criteria; and (5) show the simulated optical qualityand/or visual performance provided by each of the proposed IOL modelsfor distance and/or for any other vergence or field angle.

An improved method for selecting an intraocular lens may include thecalculation of the posterior corneal astigmatism and total corneal powerof the eye. An accurate method to calculate these two quantities may becomprised of a first step of measuring the anterior corneal shape with atopographer, a second step of measuring a corneal thickness map with ascanning optical coherence tomographer, and a third step of adding thethickness map to the anterior surface shape to obtain the shape of theposterior surface. For highest accuracy, the bending of the opticalcoherence beam on the anterior corneal surface may be calculated usingSnell's law at each location across the cornea prior to the step ofadding the thickness map to the anterior cornea shape. After thedetermination of posterior corneal shape, the posterior cornealastigmatism and total corneal power may be calculated using standardoptical ray tracing techniques.

A method of selecting an intraocular lens (IOL) to be implanted in asubject eye, or alternatively, a tangible computer-readable storagedevice storing computer instructions which, when read by a computer,cause the computer to perform the method, comprises: measuring aplurality of eye characteristics comprising ocular biometry information,anterior corneal surface information, posterior corneal surfaceinformation, anterior lens surface information, posterior lens surfaceinformation, lens tilt information, and lens position information; andfor each of Intraocular Lens (“IOL”) model having associated with it aplurality of predetermined parameters selected from the group consistingof dioptic power, refractive index, anterior and posterior radius, IOLthickness, asphericity, toricity, echelette design, haptic angulation,and lens filter: (1) modeling the subject eye with the intraocular lens;(2) simulating the subject eye based on the plurality of IOLpredetermined parameters and the predicted IOL position; (3) performinga ray tracing and an IOL spherical equivalent (SE) and cylinder (C)power calculation, as well as determine the optimum IOL orientationbased on said eye model; and (4) proposing one IOL power for one or moreIOL models from the plurality of IOLs corresponding to the optimizedIOL(s) based on predetermined criteria; and optionally, (5) show thesimulated optical quality and/or visual performance provided by each ofthe proposed IOL models for distance and/or for any other vergence.

A method, or alternatively, a tangible computer-readable storage devicestoring computer instructions which, when read by a computer, cause thecomputer to perform the method, comprising: (1) receiving a plurality ofeye characteristics comprising ocular biometry information, anteriorcorneal surface information, posterior corneal surface information,anterior lens surface information, and posterior lens surfaceinformation, lens tilt information and lens position information; (2)for each of Intraocular Lens (“IOL”) model having associated with it aplurality of predetermined parameters selected from the group consistingof dioptic power, refractive index, anterior and posterior radius, IOLthickness, asphericity, toricity, echelette design, haptic angulation,and lens filter: simulating a geometry of the subject eye with each ofthe plurality of intraocular lenses (IOL) implanted, in accordance withthe plurality of eye characteristics; (3) performing a ray tracing andan IOL spherical equivalent (SE) and cylinder (C) power calculation, aswell as determine the optimum IOL orientation based on said eye model;(4) proposing one IOL power for one or more IOL models from theplurality of IOLs corresponding to the optimized IOL(s) based onpredetermined criteria; and, optionally (5) showing the simulatedoptical quality and/or visual performance provided by each of theproposed IOL models for distance and/or for any other vergence.

A method of predicting the intraocular lens position comprising:determining a plurality of eye characteristics before cataract surgery,comprising ocular biometry information, anterior corneal surfaceinformation, posterior corneal surface information, anterior lenssurface information, posterior lens surface information, lens tiltinformation, and lens position information; determining a plurality ofeye characteristics after cataract surgery, comprising ocular biometryinformation, anterior corneal surface information, posterior cornealsurface information, anterior lens surface information, and posteriorlens surface information, IOL tilt information and IOL positioninformation; calculating or measuring, based on a mathematicalrelationship, a distance from the apex or from the retina to a plane ofthe intraocular lens after an ocular surgical procedure; calculating anoptical power of the intraocular lens suitable for providing apredetermined refractive outcome; wherein a mathematical relationship isfound between the preoperative and postoperative eye characteristicsthat accurately predicts the measured distance from the apex or from theretina to the plane where the intraocular lens is.

An improved system for planning a treatment of an eye of a patient, thesystem comprising: a memory operable to store eye measurement datacomprising ocular biometry information, anterior corneal surfaceinformation, posterior corneal surface information, anterior lenssurface information, posterior lens surface information, lens tiltinformation, and lens position information; a processor coupled to thememory, the processor deriving the treatment of the eye of the patientapplying an effective treatment transfer function, wherein the effectivetreatment transfer function is derived from, for each of a plurality ofprior eye treatments, a correlation between a pre-treatment vectorcharacterizing the eye measurement data before treatment, and apost-treatment vector characterizing post-treatment eye measurement dataof the associated eye; an output coupled to the processor so as totransmit the treatment to facilitate improving refraction and/or higherorder aberration and/or optical quality of the eye of the patient forone or multiple vergences and/or field angles. The processor preferablycomprises tangible media embodying machine readable instructions forimplementing the derivation of the treatment.

An improved method for planning a refractive treatment of an eye of apatient, the method comprising: measuring a plurality of ocular biometryinformation, anterior corneal surface information, posterior cornealsurface information, anterior lens surface information, and posteriorlens surface information, lens tilt information, and lens positioninformation.

A method of customizing at least one parameter of an intraocular lens,comprising: measuring a plurality of eye characteristics comprisingocular biometry information, anterior corneal surface information,posterior corneal surface information, anterior lens surfaceinformation, posterior lens surface information, lens tilt information,and lens position information; determining a desired postoperativecondition of the eye; empirically calculating a post-operative conditionof the eye based at least partially on the measured eye characteristics;and predictively estimating, in accordance with an output of saidempirically calculating the post-operative condition and the eyecharacteristics, the at least one parameter of the intraocular lens toobtain the desired postoperative condition.

A method of adjusting the refraction in an eye of a patient who hasundergone cataract surgery comprising: measuring a plurality ofpost-operative eye characteristics in an eye of a patient who haspreviously undergone cataract surgery, the eye characteristicscomprising ocular biometry information, anterior corneal surfaceinformation, posterior corneal surface information, anterior lenssurface information, and posterior lens surface information, lens tiltinformation and lens position information; identifying a plurality ofcorrective procedure based at least partially on one of (1) a comparisonof at least one measured pre-operative eye characteristic and thecorresponding measured post-operative eye characteristic; and (2) acomparison of at least one predicted post-operative eye characteristicand the corresponding measured post-operative eye characteristic; foreach of a plurality of corrective procedures: modeling the subject eyewith the corrective procedure; modeling the subject eye based on thecorrective procedure; performing one of a ray tracing and a powercalculation based on said eye model; and selecting a correctiveprocedure from the plurality of IOL models corresponding to theoptimized IOL based on a predetermined criteria.

In some embodiments, the system further comprises a processor configuredto execute an algorithm. The algorithm comprises, for each of the IOLmodels: (1) modeling the subject's eye with an intraocular lenscorresponding to the IOL model and the measured characteristics of thesubject's eye; (2) simulating the subject's eye based on the pluralityof IOL predetermined parameters and the predicted IOL position; (3)performing one of a ray tracing and a power calculation based on saidmodel of the subject's eye; and (4) selecting an IOL from the pluralityof IOL models corresponding to the optimized IOL based on apredetermined criteria.

In some embodiments, the system further comprises a processor configuredto execute an algorithm. The algorithm comprises: determining a desiredpostoperative condition of the subject's eye; empirically calculating apost-operative condition of the subject's eye based at least partiallyon the one or more measured characteristics of the subject's eye; andpredictively estimating, in accordance with an output of saidempirically calculating and the eye characteristics, at least oneparameter of an intraocular lens for implantation into the subject's eyeto obtain the desired postoperative condition.

This summary and the following detailed description are merelyexemplary, illustrative, and explanatory, and are not intended to limit,but to provide further explanation of the invention as claimed.Additional features and advantages of the invention will be set forth inthe descriptions that follow, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription, claims and the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages will be facilitated by referring to the following detaileddescription that sets forth illustrative embodiments using principles ofthe invention, as well as to the accompanying drawings, in which likenumerals refer to like parts throughout the different views. Like parts,however, do not always have like reference numerals. Further, thedrawings are not drawn to scale, and emphasis has instead been placed onillustrating the principles of the invention. All illustrations areintended to convey concepts, where relative sizes, shapes, and otherdetailed attributes may be illustrated schematically rather thandepicted literally or precisely.

FIG. 1A illustrates a front perspective view showing an opticalmeasurement system according to many embodiments.

FIG. 1B illustrates a rear perspective view showing an opticalmeasurement system according to many embodiments.

FIG. 1C illustrates a side perspective view showing an opticalmeasurement system according to many embodiments.

FIG. 2 is a block diagram of a system including an optical measurementinstrument, and a position of an eye relative to the system according toone or more embodiments described herein which may be used by theoptical measurement.

FIGS. 3A and 3B illustrate together an assembly illustrating a suitableconfiguration and integration of an optical coherence tomographersubsystem, a wavefront aberrometer subsystem, a corneal topographersubsystem, an iris imaging subsystem, a fixation target subsystemaccording to a non-limiting embodiment of the present invention.

FIG. 4 is a block diagram of an OCT assembly according to manyembodiments of the present invention.

FIG. 5 is a schematic drawing of a human eye.

FIG. 6A illustrates a preferred scanning region for the OCT subsystemaccording to many embodiments of the present invention.

FIG. 6B shows a representative graph of an intensity of an OCT signal ofan OCT subsystem 190 according to many embodiments as a function ofdepth along the axis defining the axial length of the eye.

FIG. 6C shows a cross-section of an eye obtained by an opticalmeasurement system of the present invention using an OCT subsystemaccording to the present invention

FIG. 7 is a 3-dimensional representation of an anterior portion of aneye obtained using the optical measurement system according to manyembodiments.

FIG. 8 is a flowchart of an example embodiment of a method forperforming cataract diagnostics for an eye with an optical measurementinstrument according to one embodiment described herein, includingwavefront aberrometry, corneal topography and OCT measurements atvarious locations with the eye along the axial length of the eye.

FIG. 9 is a flowchart of another example embodiment of a method forperforming cataract diagnostics for an eye with an optical measurementinstrument.

FIG. 10 is a flowchart of another example embodiment of a method forperforming cataract diagnostics for an eye with an optical measurementinstrument in which OCT measurements and iris imaging may be performedsimultaneously.

FIG. 11 is a flowchart of yet another example embodiment of a method forperforming cataract diagnostics for an eye with an optical measurementinstrument in which OCT measurements and iris imaging may be performedsimultaneously.

FIG. 12 illustrates another embodiment of a suitable configuration andintegration of an optical coherence tomographer subsystem, a wavefrontaberrometer subsystem, a corneal topographer subsystem, an iris imagingsubsystem, a fixation target subsystem and a posterior cornealastigmatism subsystem according to a non-limiting embodiment of thepresent invention.

FIG. 13A illustrates an image obtained from a near detector of aposterior corneal astigmatism subsystem according to a non-limitingembodiment of the present invention.

FIG. 13B illustrates an image obtained from a far detector of an aposterior corneal astigmatism assembly according to a non-limitingembodiment of the present invention.

FIG. 14 illustrates an alternate having near and far detectors that canbe used to determine a total corneal astigmatism.

FIG. 15 shows the far and near detectors operating as a separate systemto determine a total corneal astigmatism.

FIG. 16 shows an embodiment of FIG. 15 in which a corneal topographerhas been added.

DETAILED DESCRIPTION

Exemplary embodiments of optical measurement systems and methods forcataract diagnostics to illustrate various aspects and advantages ofthese devices and methods are described below. It should be understood,however, that these devices and methods involve principles that can beemployed in a variety of other contexts, and therefore, the noveldevices and method disclosed and claimed here should not be construed asbeing limited to the examplary embodiments described below.

As shown in FIGS. 1A-1C, an optical measurement system 1, according tomany embodiments, is operable to provide for a plurality of measurementsof the human eye, including measurements of the cornea, the lenscapsule, the lens and the retina. The main unit 2 comprises a base 3 andincludes many primary subsystems of many embodiments of the system 1.For example, externally visible subsystems include a touch-screendisplay control panel 7, a patient interface assembly 4 and a joystick8.

The patient interface 4 preferably includes one or more structuresconfigured to hold a patient's head in a stable, immobile and preferablycomfortable position during the diagnostic measurements while alsomaintaining the eye of the patient in a suitable alignment with thediagnostic system. In a particularly preferred embodiment, the eye ofthe patient remains in substantially the same position relative to thediagnostic system for all diagnostic and imaging measurements performedby the system 1.

In one embodiment, the patient interface includes a chin support 6and/or a forehead rest 5 configured to hold the head of the patient in asingle, uniform position suitably aligned with respect to the system 1throughout the diagnostic measurement. As shown in FIG. 1C, the opticalmeasurement system 1 is preferably disposed so that the patient may beseated in a patient chair 9. The patient chair 9 can be configured to beadjusted and oriented in three axes (x, y, and z) so that the patent'shead can be at a suitable height and lateral position for placement onthe patient interface.

In many embodiments, the system 1 may include external communicationconnections. For example, the system 1 can include a network connection(e.g., an RJ45 network connection) for connecting the system 1 to anetwork. The network connection can be used to enable network printingof diagnostic reports, remote access to view patient diagnostic reports,and remote access to perform system diagnostics. The system 1 caninclude a video output port (e.g., HDMI) that can be used to outputvideo of diagnostic measurements performed by the system 2. The outputvideo can be displayed on an external monitor for, for example, viewingby physicians or users. The output video can also be recorded for, forexample, archival purposes. The system 2 can include one or more dataoutput ports (e.g., USB) to enable export of patient diagnostic reportsto, for example, a data storage device or a computer readable medium,for example a non-volatile computer readable medium, coupled to a lasercataract surgery device for use of the diagnostic measurements inconducting laser cataract surgeries. The diagnostic reports stored onthe data storage device or computer readable medium can then be accessedat a later time for any suitable purpose such as, for example, printingfrom an external computer in the case where the user without access tonetwork based printing or for use during cataract surgery, includinglaser cataract surgery.

FIG. 2 is a block diagram of a system including an optical measurementinstrument 1 according to one or more embodiments described herein.Optical measurement instrument 1 includes: an optical coherencetomographer (OCT) subsystem 10, a wavefront aberrometer subsystem 20,and a corneal topographer subsystem 30 for measuring one or morecharacteristics of a subject's eye. Optical measurement instrument 1 mayfurther include an iris imaging subsystem 40, a fixation targetsubsystem 50, a controller 60, including one or more processor(s) 61 andmemory 62, a display 70 and an operator interface 80. Opticalmeasurement instrument 1 further includes a patient interface 4 for asubject to present his or her eye for measurement by optical measurementinstrument 1.

The optical coherence tomography subsystem 10 is configured to measurethe spatial disposition (e.g., three-dimensional coordinates such as X,Y, and Z of points on boundaries) of eye structures in three dimensions.Such structure of interest can include, for example, the anteriorsurface of the cornea, the posterior surface of the cornea, the anteriorportion of the lens capsule, the posterior portion of the lens capsule,the anterior surface of the crystalline lens, the posterior surface ofthe crystalline lens, the iris, the pupil, the limbus and/or the retina.The spatial disposition of the structures of interest and/or of suitablematching geometric modeling such as surfaces and curves can be generatedand/or used by the controller for a number of purposes, including, insome embodiment to program and control a subsequent laser-assistedsurgical procedure. The spatial disposition of the structures ofinterest and/or of suitable matching geometric modeling can also be usedto determine a wide variety of parameters.

As a non-limiting example, the system 1 can be configured to use a sweptsource OCT imaging system employing wavelengths of around 1060 nm withan 8 mm scan depth. The spatial disposition of the eye structures usingoptical coherence tomography should generally be measured while thepatient is engaged with patient interface 4. The OCT scan depth ispreferably between 8 and 50 mm, and the scan depth is preferably greaterthan about 24 mm or even 30 mm to achieve a full eyescan depth. Theswept source wavelengths can be centered at wavelengths from 840 nm to1310 nm. Optical coherence tomographer subsystem 10 is only one exampleof an eye structure imaging subsystem which may be employed in opticalmeasurement instrument 1. In other embodiments, a different eyestructure imaging subsystem may be employed, for example a Scheimpflugimager, a fluorescence imager, a structured lighting imager, a wavefronttomographer, an ultrasound imager, and a plenoptic imager.

The wavefront aberrometer subsystem 20 is configured to measure ocularaberrations, preferably including low and high order aberrations, bymeasuring the wavefront emerging from the eye by, for example a ShackHartman sensor

The corneal topographer subsystem 30 may apply any number of modalitiesto measure the shape of the cornea including one or more of akeratometry reading of the eye, a corneal topography of the eye, anoptical coherence tomography of the eye, a Placido style disc topographyof the eye, a reflection of a plurality of points from the cornealtopography of the eye, a grid reflected from the cornea of the eyetopography, a Hartmann-Shack measurement of the eye, a Scheimpflug imagetopography of the eye, a confocal tomography of the eye, a Helmholtzsource topographer, or a low coherence reflectometry of the eye. Theshape of the cornea should generally be measured while the patient isengaged with patient interface 4.

Fixation target system 50 is configured to control the patient'saccommodation, because it is often desired to measure the refraction andwavefront aberrations when eye 101 is focused at its far point

Images captured by the corneal topographer subsystem 10, the wavefrontaberrometer 20, the optical coherence tomographer subsystem 30 or thecamera 40 may be displayed with a display of the operator interface 80of the optical measurement system 2 or the display 70 of the opticalmeasurement system, respectively. The operator interface may also beused to modify, distort, or transform any of the displayed images.

The shared optics 55 provide a common propagation path that is disposedbetween the patient interface 4 and each of the optical coherencetomographer (OCT) subsystem 10, the wavefront aberrometer subsystem 20,the corneal topographer subsystem 30, and in some embodiments, anoptional posterior corneal astigmatism subsystem 35, an iris imagingsubsystem 40, and a fixation target subsystem 50. In many embodiments,the shared optics 55 may comprise a number of optical elements,including mirrors, lenses and beam combiners to receive the emissionfrom the respective subsystem to the patient's eye and, in some cases,to redirect the emission from a patient's eye along the commonpropagation path to an appropriate director.

The controller 60 controls the operation of the optical measurementinstrument 1 and can receive input from any of the optical coherencetomographer (OCT) subsystem 10, the wavefront aberrometer subsystem 20,the corneal topographer subsystem 30 for measuring one or morecharacteristics of the cornea of a subject's eye, the optional posteriorcorneal astigmatism subsystem, the iris imaging subsystem 40, thefixation target 50, the display 70 and the operator interface 80 via thecommunication paths 58. The controller 60 can include any suitablecomponents, such as one or more processor, one or morefield-programmable gate array (FPGA), and one or more memory storagedevices. In many embodiments, the controller 60 controls the display 70to provide for user control over the laser eye surgery procedure forpre-cataract procedure planning according to user specified treatmentparameters as well as to provide user control over the laser eye surgeryprocedure. The communication paths 58 can be implemented in any suitableconfiguration, including any suitable shared or dedicated communicationpaths between the controller 60 and the respective system components.

The operator interface 80 can include any suitable user input devicesuitable to provide user input to the controller 60. For example, theuser interface devices 80 can include devices such as joystick 8, akeyboard or a touchscreen display 70.

FIGS. 3A and 3B are simplified block diagrams illustrating an assembly100 according to many embodiments, which can be included in the system1. The assembly 100 is a non-limiting example of suitable configurationsand integration of the optical coherence tomographer (OCT) subsystem190, the wavefront aberrometer subsystem 150, the corneal topographersubsystem 140 for measuring one or more characteristics of a subject'seye, an iris imaging subsystem 40, the fixation target subsystem 180 andthe shared optics.

The shared optics generally comprise one or more components of a firstoptical system 170 disposed along a central axis 102 passing through theopening or aperture 114 of the structure 110. A first optical system 170directs light from the various light sources along the central axis 102towards the eye and establishes a shared or common optical path alongwhich the light from the various light sources travel to the eye 101. Inone embodiment, optical system 170 comprises a quarter wave plate 171, afirst beamsplitter 172, a second beamsplitter 173, an optical element(e.g., a lens) 174, a second lens 175, a third beamsplitter 176, and astructure including an aperture 178. Additional optical systems may beused in assembly 100 to direct light beams from one or more lightsources to the first optical system 170. For example, a second opticalsystem 160 directs light to the first optical system 170 from thewavefront aberrometer subsystem 150 and comprises mirror 153, beamsplitter 162 and beam splitter 183, and lens 185.

Other embodiments of suitable systems for the measurement of refractiveerror, and particularly to methods and techniques for compiling a topput graphic mapping of refractive errors include: U.S. Pat. No.6,550,917, filed Oct. 20, 2000, entitled “Dynamic Range ExtensionTechniques For A Wavefront Sensor Including Use In OphthalmicMeasurement”; U.S. Pat. No. 6,908,196, filed Feb. 21, 2003, entitled“System And Method For Performing Optical Corrective Procedures WithReal-Time Feedback”; U.S. Pat. No. 7,455,407, filed Apr. 21, 2004,entitled “System And Method Of Measuring And Mapping Three DimensionalStructures”; U.S. Pat. No. 7,553,022, filed Jul. 27, 2007, entitled“System And Method Of Measuring And Mapping Three DimensionalStructures”; U.S. Pat. No. 7,988,292, filed May 29, 2009, entitled“System And Method Of Measuring And Mapping Three DimensionalStructures”; and WO2001/058339, filed Feb. 8, 2001, entitled “DynamicRange Extension Techniques For A Wavefront Sensor.” These references arehereby incorporated herein by reference in their entirety as if fullyset forth.

Other configurations of the assembly 100, such as liquid lensconfigurations, may be possible and may be apparent to a person of skillin the art.

The corneal topographer subsystem 140 comprises a structure 110 having aprincipal surface 112 with an opening or aperture 114 therein; aplurality of first (or peripheral) light sources 120 provided on theprincipal surface 112 of the structure 110; a Helmholz light source 130;and a detector, photodetector, or detector array 141.

In one embodiment, structure 110 has the shape of an elongated oval or“zeppelin” with openings or apertures at either end thereof. An exampleof such a structure is disclosed in Yobani Meji'a-Barbosa et al.,“Object surface for applying a modified Hartmann test to measure cornealtopography,” APPLIED OPTICS, Vol. 40, No. 31 (Nov. 1, 2001)(“Meji'a-Barbosa”). In some embodiments, principal surface 112 ofstructure 110 is concave when viewed from the cornea of eye 101, asillustrated in FIG. 1A.

In one embodiment, where principal surface 112 is concave, principalsurface 112 has the shape of a conical frustum. Alternatively, principalsurface 112 may have a shape of hemisphere or some other portion of asphere, with an opening or aperture therein. Also alternatively,principal surface 112 may have the shape of a modified sphere or conicalfrustum, with a side portion removed. Beneficially, such an arrangementmay improve the ergonomics of assembly 100 by more easily allowingstructure 110 to be more closely located to a subject's eye 101 withoutbeing obstructed by the subject's nose. Of course, a variety of otherconfigurations and shapes for principal surface 112 are possible.

In the embodiment of FIG. 1A, the plurality of first light sources 120are provided on the principal surface 112 of structure 110 so as toilluminate the cornea of eye 101. In one embodiment, light sources 122may comprise individual light generating elements or lamps, such aslight emitting diodes (LEDs) and/or the tips of the individual opticalfibers of a fiber bundle. Alternatively, principal surface 112 ofstructure 110 may have a plurality of holes or apertures therein, andone or more backlight lamps, which may include reflectors and/ordiffusers, may be provided for passing lighting through the holes toform the plurality of first light sources 120 which project light ontothe cornea of eye 101. Other arrangements are possible.

Other embodiments of suitable systems include: U.S. Pat. No. 8,126,246,filed Jan. 8, 2009, entitled “Systems And Methods For Measuring SurfaceShape”; U.S. Pat. No. 8,260,024, filed Jan. 23, 2012, entitled “SystemsAnd Methods For Measuring Surface Shape”; and European PatentApplication No. 20090701204, filed Jan. 8, 2008, entitled “Systems AndMethods For Measuring Surface Shape.” These references are herebyincorporated herein by reference in their entirety as if fully setforth.

In another embodiment, structure 110 is omitted from assembly 100, andthe first light sources 120 may be independently suspended (e.g., asseparate optical fibers) to form a group of first light sources 120arranged around a central axis, the group being separated from the axisby a radial distance defining an aperture in the group (correspondinggenerally to the aperture 114 in the structure 110 illustrated in FIG.1A).

In operation, a ray (solid line) from one of the first light sources 120is reflected by the cornea and passes through optical system 170(including aperture 178) to appear as a light spot on detector array141. It will be appreciated that this ray is representative of a smallbundle of rays that make it through optical system 170 and onto detectorarray 141, all of which will focus to substantially the same location ondetector array 141. Other rays from that first light source 120 areeither blocked by the aperture 178 or are otherwise scattered so as tonot pass through the optical system 170. In similar fashion, light fromthe other first light sources 120 are imaged onto detector array 141such that each one of first light sources 120 is imaged or mapped to alocation on detector array 141 that may be correlated to a particularreflection location on the cornea of eye 101 and/or the shape of thecornea. Thus, detector array 141 detects the light spots projectedthereon and provides corresponding output signals to a processor ofcontroller 60 (FIG. 2). The processor determines the locations and/orshape of the light spots on detector array 141, and compares theselocations and/or shapes to those expected for a standard or modelcornea, thereby allowing the processor of controller 60 to determine thecorneal topography. Alternatively, other ways of processing the spotimages on detector array 141 may be used to determine the cornealtopography of eye 101, or other information related to thecharacterization of eye 101.

Detector array 141 comprises a plurality of light detecting elementsarranged in a two dimensional array. In one embodiment, detector array141 comprises such a charge-coupled device (CCD), such as may be foundin a video camera. However, other arrangements such as a CMOS array, oranother electronic photosensitive device, may be employed instead.Beneficially, the video output signal(s) of detector array 141 areprovided to processor 61 which processes these output signals asdescribed in greater detail below.

Assembly 100 also comprises a Helmholtz light source 130 configuredaccording to the Helmholtz principle. As used herein, the term“Helmholtz source” or “Helmholtz light source” means one or a pluralityof individual light sources disposed such that light from each of theindividual light sources passes through an optical element havingoptical power, reflects off of a reference or test object, passesthrough the optical element, and is received by a detector, whereinlight from the Helmholtz source is used to determine geometric and/oroptical information of at least a portion of a surface of the referenceor test object. In general, it is a characteristic of Helmholtz sourcesthat the signal at the detector is independent of the relative positionof the test or reference object relative to the Helmholtz source. Asused herein, the term “optical element” means an element that refracts,reflects, and/or diffracts light and has either positive or negativeoptical power.

In such embodiments, the Helmholtz light source 130 is located atoptical infinity with respect to eye 101. The Helmholtz principleincludes the use of such infinite sources in combination with atelecentric detector system: i.e., a system that places the detectorarray at optical infinity with respect to the surface under measurement,in addition to insuring that the principal measured ray leaving thesurface is parallel to the optical axis of the instrument. The Helmholtzcorneal measurement principle has the Helmholtz light source at opticalinfinity and the telecentric observing system so that detector array 141is also optically at an infinite distance from the images of the sourcesformed by the cornea. Such a measurement system is insensitive to axialmisalignment of the corneal surface with respect to the instrument.

In one embodiment, the Helmholtz light source 130 comprises a secondlight source 132 which may comprise a plurality of lamps, such as LEDsor optical fiber tips. In one embodiment, second light source 132comprises an LED and a plate 133 with plurality of holes or apertures ina surface that are illuminated by one or more backlight lamps with anoptical element 131, which may comprise diffusers.

In one embodiment, second light sources 132 are located off the centraloptical axis 102 of assembly 100, and light from second light sources132 is directed toward optical element 171 by third beamsplitter 176.

The operation of the topographer portion of system 100 may be conductedwith the combined use of first light source 120 and the Helmholz lightsource 130. In operation, detector array 141 detects the light spotsprojected thereon from both Helmholz light source 130 (detected at acentral portion of detector array 141) and first light sources 120(detected at a peripheral portion of detector array 141) and providescorresponding output signals to processor. In general, the images offirst light sources 120 that appear on detector array 140 emanate froman outer region of the surface of the cornea, and the images of Helmholzlight source 130 that appear on detector array 141 emanate from acentral or paraxial region of the surface of the cornea. Accordingly,even though information about the central region of the corneal surface(e.g., surface curvature) cannot be determined from the images of firstlight sources 120 on detector array 141, such information can bedetermined from the images of Helmholz light source 130 on detectorarray 141. A processor of controller 60 determines the locations and/orshapes of the light spots on detector array 141, and compares theselocations and/or shapes to those expected based for a standard or modelcornea, thereby allowing the processor to determine the cornealtopography of eye 101. Accordingly, the topography of the entire cornealsurface can be characterized by system 100 without a “hole” or missingdata from the central corneal region.

A fourth light source 201 off the central axis 102 may be directed alongoptical axis 102 by mirrors 177, 179 disposed on or near the aperture178, perpendicular to the optical axis 102 are configured as a pupilretroreflection illuminator. The pupil retroreflecton illuminator isconfigured to direct a disc of light toward a patient's eye, whereby thedisc of light may be reflected from reflective surfaces within the eye,and the reflected light is transmitted by optical path 170 to detector141. The pupil retroreflection illuminators may optionally be configuredsuch that, when a patient's pupil is dilated, the disc of light fromlight source 201 is reflected from an implanted IOL to image the IOL,including any fiducial marks; if IOL is imperfectly placed, detector 141may be used to determine IOL edges are decentered. Also, images fromdetector 141 using the pupil retroreflection illuminator may see folds,for instance, unfolded edge if the IOL did not unfold properly.

The wavefront aberrometer subsystem 150 of the assembly 100 comprises athird light source 152 providing a probe beam and a wavefront sensor155. The wavefront aberrometer subsystem 150 preferably furthercomprises a collimating lens 154, a polarizing beamsplitter 156, anadjustable telescope comprising a first optical element, lens 163 and asecond optical element, lens 164, a movable stage or platform 166, and adynamic-range limiting aperture 165 for limiting a dynamic range oflight provided to wavefront sensor 155 so as to preclude data ambiguity.Light from the wavefront aberrometer subsystem is directed to one of theconstituent optical elements of the optical system 170 disposed along acentral axis 102 passing through the opening or aperture 114 of thestructure 110. It will be appreciated by those of skill in the art thatthe lenses 163, 164, or any of the other lenses discussed herein, may bereplaced or supplemented by another type of converging or divergingoptical element, such as a diffractive optical element.

Light source 152 is preferably an 840 nm SLD (super luminescent laserdiode). An SLD is similar to a laser in that the light originates from avery small emitter area. However, unlike a laser, the spectral width ofthe SLD is very broad, about 40 nm. This tends to reduce speckle effectsand improve the images that are used for wavefront measurements.

Preferably, wavefront sensor 155 is a Shack-Hartmann wavefront sensorcomprising a detector array and a plurality of lenslets for focusingreceived light onto its detector array. In that case, the detector arraymay be a CCD, a CMOS array, or another electronic photosensitive device.However, other wavefront sensors may be employed instead. Embodiments ofwavefront sensors which may be employed in one or more systems describedherein are described in U.S. Pat. No. 6,550,917, issued to Neal et al.on Apr. 22, 2003, and U.S. Pat. No. 5,777,719, issued to Williams et al.on Jul. 7, 1998, both of which patents are hereby incorporated herein byreference in their entirety.

The aperture or opening in the middle of the group of first lightsources 120 (e.g., aperture 114 in principal surface 112 of structure110) allows system 100 to provide a probe beam into eye 101 tocharacterize its total ocular aberrations. Accordingly, third lightsource 152 supplies a probe beam through a light source polarizing beamsplitter 156 and polarizing beam splitter 162 to first beamsplitter 172of optical system 170. First beamsplitter 172 directs the probe beamthrough aperture 114 to eye 101. Preferably, light from the probe beamis scattered from the retina of eye 101, and at least a portion of thescattered light passes back through aperture 114 to first beamsplitter172. First beamsplitter 172 directs the back scattered light backthrough beam splitter 172 to polarizing beamsplitter 162, mirror 153, towavefront sensor 155.

Wavefront sensor 155 outputs signals to a processor of controller 60which uses the signals to determine ocular aberrations of eye 101.Preferably, processor 141 is able to better characterize eye 101 byconsidering the corneal topography of eye 101 measured by the CornealTopography Subsystem, which may also be determined by processor 141based on outputs of detector array 141, as explained above.

In operation of the wavefront aberrometer subsystem 150, light fromlight source 152 is collimated by lens 154. The light passes throughlight source polarizing beam splitter 156. The light entering lightsource polarizing beam splitter 156 is partially polarized. Light sourcepolarizing beam splitter 156 reflects light having a first, S,polarization, and transmits light having a second, P, polarization sothe exiting light is 100% linearly polarized. In this case, S and Prefer to polarization directions relative to the hypotenuse in lightsource polarizing beam splitter 156.

Light from light source polarizing beam splitter 156 enters polarizingbeamsplitter 162. The hypotenuse of polarizing beamsplitter 162 isrotated 90 degrees relative to the hypotenuse of light source polarizingbeamsplitter 156 so the light is now S polarized relative the hypotenuseof polarizing beamsplitter 162 and therefore the light reflects upwards.The light from polarizing beamsplitter 162 travels upward and passesthrough toward beam splitter 172, retaining its S polarization, and thentravels through quarter wave plate 171. Quarter wave plate 171 convertsthe light to circular polarization. The light then travels throughaperture 114 in principal surface 112 of structure 110 to eye 101.Preferably, the beam diameter on the cornea is between 1 and 2 mm. Then,the light travels through the cornea and focuses onto the retina of eye101.

The focused spot of light becomes a light source that is used tocharacterize eye 101 with wavefront sensor 155. Light from the probebeam that impinges on the retina of eye 101 scatters in variousdirections. Some of the light reflects back as a semi-collimated beamback towards assembly 100. Upon scattering, about 90% of the lightretains its polarization. So the light traveling back towards assemblyis substantially still circularly polarized. The light then travelsthrough aperture 114 in principal surface 112 of structure 110, throughquarterwave plate 171, and is converted back to linear polarization.Quarterwave plate 171 converts the polarization of the light from theeye's retina so that it is P polarized, in contrast to probe beamreceived from third light source 150 having the S polarization. This Ppolarized light then reflects off of first beamsplitter 172, and thenreaches polarizing beamsplitter 162. Since the light is now P polarizedrelative the hypotenuse of polarizing beamsplitter 162, the beam istransmitted and then continues onto mirror 153. After being reflected bymirror 153, light is sent to an adjustable telescope comprising a firstoptical element 164 and a second optical element (e.g., lens) 163 and amovable stage or platform 166. The beam is also directed through adynamic-range limiting aperture 165 for limiting a dynamic range oflight provided to wavefront sensor 155 so as to preclude data ambiguity.

When wavefront sensor 155 is a Shack-Hartmann sensor, the light iscollected by the lenslet array in wavefront sensor 155 and an image ofspots appears on the detector array (e.g., CCD) in wavefront sensor 155.This image is then provided to a process of the controller 60 andanalyzed to compute the refraction and aberrations of eye 101.

An OCT subsystem 190 of assembly 100 preferably comprises an OCTassembly 191, and a third optical path 192 which directs the OCT beam ofthe OCT light source to the first optical path 170. The third opticalpath 192 preferably comprises a fiber optic line 196, for conducting theOCT beam from the OCT light source, a z-scan device 193 operable toalter the focus of the beam in the z-direction (i.e., along thedirection of propagation of the OCT beam) under control of thecontroller, and x-scan device 195, and a y-scan device 197 operable totranslate the OCT beam in the x and y directions (i.e., perpendicular tothe direction of propagation of the of the OCT beam), respectively,under control of the controller. A first set 198 of polarizationcontrollers may optionally be included to change a polarization propertyof the OCT light source. The OCT light source and reference arm may beincorporated into the main unit 4 of the optical measurement instrument1 shown in FIG. 1A. Alternatively, the OCT assembly 191 may be housed ina second unit 200 and the OCT beam from the OCT source may be directedfrom the second housing 200 to the main unit by optical pathway 192.

The OCT systems and methods of the present invention are preferablyFD-OCT (Fourier domain optical coherence tomography) systems, includingeither an SD-OCT (spectral domain optical coherence tomography) systemor, more preferably, an SS-OCT (swept source optical coherencetomography) system. In conventional FD-OCT systems, the interferencesignal is distributed and integrated over numerous spectral wavelengthintervals, and is inverse Fourier transformed to obtain thedepth-dependent reflectivity profile of the sample. The profile ofscattering as a function of depth is referred to as an A-scan(Axial-scan). The beam can be scanned laterally to produce a set ofA-scans that can be combined together to form a tomogram of the sample(a B-scan).

In an SD-OCT system, various spectral wavelength intervals of thecombined returned light from the reference and sample arms are spatiallyencoded using, for instance, a collimator, diffraction grating, and alinear detector array. Resampling of the data obtained from the lineardetector array is performed in order to correct for the nonlinearspatial mapping of wavenumbers. After resampling and subtraction of thedc background, the depth profile structural information is obtained byperforming the inverse Fourier transform operation. In swept-source OCT,the broad bandwidth optical source is replaced by a rapid-scanning lasersource. By rapidly sweeping the source wavelength over a broadwavelength range, and collecting all the scattering information at eachwavelength and at each position, the composition of the collected signalis equivalent to the spectral-domain OCT technique. The collectedspectral data is then inverse Fourier transformed to recover the spatialdepth-dependent information.

FD-OCT suffers from an inherent sample-independent limited depth range,typically between 1 and 5 mm One limitation flows from the fact thatFD-OCT extracts depth information from the inverse Fourier transform ofa spectral interferogram. Since the spectral interferogram can only berecorded as a real signal, its Fourier transform is necessarilyHermitian symmetric about the zero path length difference (ZPD)position. As a result, the positive and negative displacements about theZPD cannot be unambiguously resolved, which gives rise to mirror imageartifacts and generally halves the useable range. This is referred to asthe complex conjugate ambiguity. Another limitation is a sensitivityfall-off which results in reduced sensitivity with increasing depth.Moreover, since the signal in OCT is derived only from backscatteredphotons, optical attenuation from absorption and scattering generallyresult in a useable imaging depth of about 1-4 mm.

Several “full range” OCT techniques have been developed that eliminatethe complex conjugate artifacts to effectively double the measurementrange around the ZPD position. These full range OCT techniques result inuseable imaging depths of up to about 5 mm or even up to about 8 mm.Suitable full range techniques include methods that dither the referenceleg length (M. Wijtkowski, et al, Opt. Lett. V27, #16, pg 1415, 2002),or that exploit phase dispersion compensation (Kottig, et al, Opt.Express V20, #22, pg 24925, 2012) to break the phase ambiguity.

As shown in FIG. 4, the OCT assembly 191 of OCT subsystem 190 includes abroadband or a swept light source 202 that is split by a coupler 204into a reference arm 206 and a sample arm 210. The reference arm 206includes a module 208 containing a reference reflection along withsuitable dispersion and path length compensation. The sample arm 210 ofthe OCT assembly 191 has an output connector 212 that serves as aninterface to the rest of the optical measurement instrument. The returnsignals from both the reference and sample arms 206, 210 are thendirected by coupler 204 to a detection device 220, which employs one oftime domain, frequency, or single point detection techniques. In FIG. 4,a swept source technique is used with a laser wavelength of 1060 nmswept over a range of 8-50 mm depth. A second set 218 of polarizationcontrollers may be used to change a polarization property of thereference beam of the reference arm.

FIG. 5 is a schematic drawing of a human eye 400. In many embodiments, alight beam 401 from a light source enters the eye from the left of FIG.5, refracts into the cornea 410, passes through the anterior chamber404, the iris 406 through the pupil, and reaches lens 402. Afterrefracting into the lens, light passes through the vitreous chamber 412,and strikes the retina 476, which detects the light and converts it toan electric signal transmitted through the optic nerve to the brain (notshown). The vitreous chamber 412 contains the vitreous humor, a clearliquid disposed between the lens 402 and retina 476. As indicated inFIG. 5, cornea 410 has corneal thickness (CT), here considered as thedistance between the anterior and posterior surfaces of the cornea.Anterior chamber 404 has anterior chamber depth (ACD), which is thedistance between the anterior surface of the cornea and the anteriorsurface of the lens. Lens 402 has lens thickness (LT) which is thedistance between the anterior and posterior surfaces of the lens. Theeye has an axial length (AXL) which is the distance between the anteriorsurface of the cornea and the retina 476. FIG. 5 also illustrates that,in many subjects the lens, including the lens capsule, may be tilted atone or more angles relative to the optical axis, including an angle γrelative to the optical axis of the eye.

The optical system may also be arranged so that the movement pattern ofthe scan mirrors provides a lateral motion across the retina so that theshape of the retina may be determined. It is of particular interest tomeasure the shape and location of the depressed region of the retinanamed the foveal pit. When the patient is looking directly into theinstrument, with their line of sight aligned to the fixation target, thefoveal pit will be in center of the OCT lateral scan. This informationis beneficial in that it informs the instrument operator if the patientwas looking directly at the target when the measurement was made.Retinal scans are also useful in detecting disease conditions. In somecases, there may be an absence of a foveal pit that also is consideredan indication of a corneal abnormality.

The average axial length of the adult human eye is about 24 mm Since thefull range imaging depth of the OCT measurements are only about 5 mm to8 mm, then OCT scanning of the invention may provide for OCT scans atdifferent depths of the eye that can be combined together to form acombined OCT image of the eye. The OCT measurements of the presentinvention preferably includes OCT imaging at various depths of thepatient's eye for imaging 1) at least a portion of the retina, 2) atleast a portion of the anterior portion of the eye, including at least aportion of the cornea (anterior and posterior), iris, and lens (anteriorand posterior), and 3) performing axial eye length measurements. In apreferred embodiment, the coherence depth range of the OCT system toexceed the length of the eye so that the entire length of the eye may bemeasured at one time without the need to combine different depth ranges.In that case, however, it may still be beneficial to change the focus ofthe beam entering into the eye so that the strength of the capturedlight may be optimized for resolving different regions of the eye. Forexample, the beam may be focused on the anterior portion of the eye forincreased resolution in that region while simultaneously a measurementof the length of the whole eye is being made. Similarly, the beam may befocused on the retina for high resolution measurements in that sectionwhile simultaneously the whole eye length is being measured. For bothsituations, the scan geometry may be arranged so that while the beam isscanning across on region, the beam is substantially stationary on theother region so that even though the beam is defocused there, the returnsignal strength from the defocus region is sufficient to provide astrong signal.

FIGS. 6A-6C illustrate various aspects of the OCT subsystem 190according to various aspects of the present invention. FIG. 6Aillustrates a preferred scanning region for the OCT subsystem accordingto many embodiments of the present invention. The scanning region may bedefined from starting point 301 to ending point 302 at the anteriorportion of the eye extending in a direction transverse the direction ofpropagation of the OCT beam and also extending in a direction parallelto an axis defining the axial length of the eye to the posterior portion304 of the eye. The lateral scanning region should generally besufficiently large in the lateral direction to permit imaging of thecentral portion of the cornea, at least a portion of the iris, at leasta portion of the lens and at least of the retina. It should be notedthat a region 303 between the posterior portion of the lens and thesurface of the retina may optionally not be scanned by OCT subsystem 190because the portion 330 does not contain anatomical structure for 3Danalysis.

FIG. 6B shows a representative graph of an intensity of an OCT signal ofan OCT subsystem 190 according to many embodiments as a function ofdepth along the axis defining the axial length of the eye. The graphgenerally exhibits approximately four peaks having a complex structure:(1) a peak 310 having a doublet-like structure and generallycorresponding to a location of the cornea; (2) a peak 320 having adoublet-like structure and generally corresponding to a location of ananterior surface of the lens; (3) a peak 330 having a complex structuregenerally corresponding to a location of a posterior surface of thelens; and (4) a peak 340 generally corresponding to a location of aretina. A distance between peak 310 and peak 340 can be used tocalculate the axial length (AL) of the eye. Preferably, an OCT scan byOCT subsystem 190, including both an A-scan and B-scan, is conducted atleast one location in the anterior portion of the eye (e.g., a locationof a cornea, a location of an anterior surface of a lens and/or alocation of a posterior surface of the lens) and at least one locationin the posterior portion of the eye (e.g., at a location of a retina).In some embodiments, an OCT scan by the OCT subsystem 190, includingboth an A-Scan and a B-scan is performed at a location corresponding toeach of a location of the cornea, a location of an anterior surface ofthe lens, a location of a posterior surface of the lens, and a locationcorresponding to a retina.

It should be noted that because the OCT subsystem 190 provides for thedetection of various structures of the eye, including a location of thecornea, the OCT subsystem 190 may be used as a ranging system toprecisely align the patient in relation to the optical measurementsystem 1 of the present invention. The use of the OCT as a rangingsystem can significantly improve accuracy of corneal topographymeasurements, including keratometry measurements, which are sensitive tomisalignment of the corneal structures.

FIG. 6C shows a cross-section of an eye obtained by an opticalmeasurement system of the present invention using an OCT subsystemaccording to the present invention.

FIG. 7 shows a 3 dimensional view of an eye obtained by an opticalmeasurement system of the present invention using an OCT subsystemaccording to the present invention. FIG. 7 evidences that the OCTsubsystem of the present invention is operable to obtain biometrymeasurements according to the present invention, including the centralcorneal thickness (CCT), the anterior chamber depth (ACD), the radius ofcurvature of the anterior cornea (ROC_(AC)), the radius of curvature ofthe Posterior cornea (ROC_(PC)) and the Radius of curvature of the axiallength (ROC_(AL)).

Preferably, the OCT subsystem 190 provides sufficiently resolvedstructural information to provide a structural assessment that mayprovide a user with an indication of suitability of a particular patientfor a laser cataract procedure. In one embodiment, an OCT scan performedby the OCT subsystem 190 at or near the retina (i.e., a retina scan) issufficiently resolved to identify the foveal pit location and depth,wherein a lack of depression indicates an unhealthy retina.

In another embodiment, the optical measurement instrument 1 of thepresent invention provides one or more measurements sufficient toprovide an assessment of the tear film of a patient. In one embodiment,the tear film assessment comprises a comparison of a wavefrontaberrometry map and a corneal topography map or OCT map of the patient'seye, by, for instance, determining the irregular features in either thewavefront aberrometery or corneal topopgraphy maps This can be achievedby first fitting the surface (either wavefront or topography) to smoothfunctions such as Zemike or Taylor polynomials, and then subtractingthis smooth surface from the original surface data. The resulting map isthe residual of what does not fit a smooth surface and is highlycorrelated with the tear film (Haixia Liu, Larry Thibos, Carolyn G.Begley, Arthur Bradley, “MEASUREMENT OF THE TIME COURSE OF OPTICALQUALITY AND VISUAL DETERIORATION DURING TEAR BREAK-UP,” InvestigativeOphthalmology & Visual Science, June 2010, Vol. 51, No. 6). Adetermination of whether the tear film is broken (if not smooth); anassessment of the tear film, including tear film breakup, can also beobtained by reviewing the shape of spots on the topographer. Forinstance, a finding or indication that the tear film is disrupted, orbroken, may be based upon the shape of a spot in that, if the spots arenot round, and have, for instance, an oblong or broken up shape, itindicates that tear film is disrupted. The existence of such a disruptedtear film may indicate that K value, and other ocular measurements maynot be reliable. Further indications of the state of the tear film maybe made by comparing the OCT and the topographer, or wavefront data (SeeKob—Simultaneous Measurement of Tear Film Dynamics IOVS, July 2010, Vol.51, No. 7).

In operation, as shown in FIG. 3A, after exiting connector 212, the OCTbeam 214 is collimated, preferably using a collimating optical fiber196. Following collimating fiber 196 the OCT beam 214 is directed to anz-scan device 193 operable to change the focal point of the OCT beam ina z-direction, and x- and y-scan devices 195 and 197, which are operableto scan the OCT beam in x and y-directions perpendicular to thez-direction.

Following the collimating optical fiber 196, the OCT beam 214 continuesthrough a z-scan device 193, 194. Preferably, the z-scan device is a Ztelescope 193, which is operable to scan focus position of the OCT beam214 in the patient's eye 101 along the Z axis. For example, theZ-telescope can include a Galilean telescope with two lens groups (eachlens group includes one or more lenses). One of the lens groups movesalong the Z axis about the collimation position of the Z-telescope 193.In this way, the focus position in the patient's eye 101 moves along theZ axis. In general, there is a relationship between the motion of lensgroup and the motion of the focus point. The exact relationship betweenthe motion of the lens and the motion of the focus in the z axis of theeye coordinate system does not have to be a fixed linear relationship.The motion can be nonlinear and directed via a model or a calibrationfrom measurement or a combination of both. Alternatively, the other lensgroup can be moved along the Z axis to adjust the position of the focuspoint along the Z axis. The Z-telescope 84 functions as a z-scan devicefor changing the focus point of the OCT beam 214 in the patient's eye101. The Z-scan device can be controlled automatically and dynamicallyby the controller 60 and selected to be independent or to interplay withthe X and Y scan devices described next.

After passing through the z-scan device, the OCT beam 214 is incidentupon an X-scan device 195, which is operable to scan the OCT beam 214 inthe X direction, which is dominantly transverse to the Z axis andtransverse to the direction of propagation of the OCT beam 214. TheX-scan device 195 is controlled by the controller 60, and can includesuitable components, such as a lens coupled to a MEMS device, a motor,galvanometer, or any other well-known optic moving device. Therelationship of the motion of the beam as a function of the motion ofthe X actuator does not have to be fixed or linear. Modeling orcalibrated measurement of the relationship or a combination of both canbe determined and used to direct the location of the beam.

After being directed by the X-scan device 196, the OCT beam 214 isincident upon a Y scan device 197, which is operable to scan the OCTbeam 214 in the Y direction, which is dominantly transverse to the X andZ axes. The Y-scan device 197 is controlled by the controller 60, andcan include suitable components, such as a lens coupled to a MEMSdevice, motor, galvanometer, or any other well-known optic movingdevice. The relationship of the motion of the beam as a function of themotion of the Y actuator does not have to be fixed or linear. Modelingor calibrated measurement of the relationship or a combination of bothcan be determined and used to direct the location of the beam.Alternatively, the functionality of the X-Scan device 195 and the Y-Scandevice 197 can be provided by an XY-scan device configured to scan theOCT bean 214 in two dimensions transverse to the Z axis and thepropagation direction of the OCT beam 214. The X-scan and Y scan devices195, 197 change the resulting direction of the OCT beam 214, causinglateral displacements of OCT beam 214 located in the patient's eye 101.

The OCT sample beam 214 is then directed to beam splitter 173 throughlens 175 through quarter wave plate 171 and aperture 114 and to thepatient eye 101. Reflections and scatter off of structures within theeye provide return beams that retrace back through the patient interfacequarter wave plate 171, lens 175, beam splitter 173, y-scan device 197,x-scan device 195, z-scan device 193, optical fiber 196 and beamcombiner 204 (FIG. 3), and back into the OCT detection device 220. Thereturning back reflections of the sample arm 201 are combined with thereturning reference portion 206 and directed into the detector portionof the OCT detection device 220, which generates OCT signals in responseto the combined returning beams. The generated OCT signals that are inturn interpreted by the controller 60 to determine the spatialdisposition of the structures of interest in the patient's eye 101. Thegenerated OCT signals can also be interpreted by the controller todetermine the spatial disposition of the structures of interest in thepatient's eye 101. The generated OCT signals can also be interpreted bythe control electronics to align the position and orientation of thepatient eye within the patient interface. As the OCT information can beobtained relatively rapidly (B-scans at 200-500 scans per second) thiscan be used to provide tracking information to the patient alignmentsystem. That is, the center offset of the corneal vertex can by obtainedin x, y and z by determining the highest point in the x and y-slices,and then determining an offset from the desired alignment point. The zvalue is the difference between the highest corneal point and thedesired z location. This information can be fed to an XYZ tracker thataligns the systems either by moving the instrument, the patient's head,or internal mirrors and optical elements in the instrument.

The quarter wave plate 171 described above has the effect that lightreturning into the instrument will have its polarization rotated byninety degrees relative to the outgoing polarization. This can result ina situation that the OCT reference beam and signal light incident on thedetector 220 will have nearly orthogonal polarizations so that theinterference signal generated is extremely weak. One effective method tomaximize the signal strength is to set the relevant OCT reference andsample light beams to be linearly polarized with, for example, apolarizing controller in both the sample arm and the reference arm. Inone such embodiment, a first set 198 of polarization controllers (FIG.3A), for example a set of polarization rotating fiber paddle adjusterson the OCT source light output, set the polarization of the incidentlight on the beamsplitter 173 to be linearly polarized on that surface.Further, a second set 218 of polarization controllers (FIG. 4), such asanother set of rotating fiber paddle adjusters, are placed in thereference fiber path leading to the detector 220. Adjustment of thepolarization controllers, such as the fiber paddles, will maximize thesignal when the reference and signal polarizations match. This allowsthe system to retain the benefits of having the quarter wave plate 171for the wavefront sensing portion of the instrument while having minimalimpact on the OCT signal strength.

The quarter wave plate 171 may be zero order design at either the OCTwavelength, the wavefront sensor wavelength, or an intermediatewavelength. Practical zero order wave plates made of crossed crystallinequartz plates are low cost and will behave as nearly as ideal over thewavelength range of interests, for instance if the center wavefrontsensor wavelength is 840 nm and the center OCT wavelength is 1060 nm.Other alternatives are polymer waveplates or the more expensiveachromatic quarter wave plates.

The optical measurement systems according to the present inventionpreferably comprise an iris imaging subsystem 40. The imaging subsystem40 generally comprises an infrared light source, preferably infraredlight source 152, and detector 141. In operation light from the lightsource 152 is directed along second optical path 160 to first opticalpath 170 and is subsequently directed to eye 101 as described above.Light reflected from the iris of eye 101 is reflected back along firstoptical path 170 to detector 141. In normal use, an operator will adjusta position or alignment of system 100 in XY and Z directions to alignthe patient according to the image detector array 141. In one embodimentof the iris imaging subsystem, eye 101 is illuminated with infraredlight from light source 152. In this way, the wavefront obtained bywavefront sensor 155 will be registered to the image from detector array141.

The image that the operator sees is the iris of eye 101. The corneagenerally magnifies and slightly displaces the image from the physicallocation of the iris. So the alignment that is done is actually to theentrance pupil of the eye. This is generally the desired condition forwavefront sensing and iris registration.

Iris images obtained by the iris imaging subsystem may be used forregistering and/or fusing the multiple data sets obtained by the varioussubsystems of the present invention, by methods described for instancein “Method for registering multiple data sets,” U.S. patent applicationSer. No. 12/418,841, which is incorporated herein by reference. As setforth in application Ser. No. 12/418,841, wavefront aberrometry may befused with corneal topography, optical coherence tomography andwavefront, optical coherence tomography and topography, pachymetry andwavefront, etc. For instance, with image recognition techniques it ispossible to find the position and extent of various features in animage. Regarding iris registration images, features that are availableinclude the position, size and shape of the pupil, the position, sizeand shape of the outer iris boundary (OIB), salient iris features(landmarks) and other features as are determined to be needed. Usingthese techniques, both patient movement between measurements (and/orduring a measurement sequence) can be identified, as well as changes inthe eye itself (including those induced by the measurement, such aschanges in the size of the pupil, changes in pupil location, etc.).

In many embodiments, an optical measurement system according the presentincludes a target fixation subsystem 150 (FIG. 1), and an assembly 100shown in FIGS. 3A and 3B includes fixation target subsystem 180 whichincludes a fixation target 182 for the patient to view. Fixation targetsubsystem 180 is used to control the patient's accommodation, because itis often desired to measure the refraction and wavefront aberrationswhen eye 101 is focused at its far point (e.g., because LASIK treatmentsare primarily based on this). Cylindrical correction and liquid lensesfor the target path may also be used. In the target fixation subsystem,a projection of a target, for instance a cross-hair pattern is projectedonto the eye of the patient, the cross hair pattern being formed by abacklit LED and a film. An alternative embodiment is to provide a videotarget that allows the projection of letters, charts, pictures ormovies. One method to control accommodation is to provide the patientwith a task “click a button each time you recognize a real word” or“click a button each time the target includes the color purple” in orderto insure that the subject is really looking and concentrating on thetarget.

In operation, light originates from the light source 152 or,alternatively, from video target backlight 182 and lens 186. Lens 185collects the light and forms an aerial image T2. This aerial image isthe one that the patient views. The patient focus is maintained onaerial image 182 during measurement so as to maintain the eye in a fixedfocal position.

The operating sequence the optical measurement system and methods of thepresent is not particularly limited. A scan of the patient's eye maycomprise one or more of a wavefront aberrometry measurement of apatient's eye utilizing the wavefront aberrometry subsystem, a cornealtopography measurement of a patient's eye and an OCT scan of thepatient's eye using the OCT subsystem, wherein the OCT scan includes ascan at each or one or more locations within the eye of the patient.These locations of the OCT scan may correspond to the location of thecornea, the location of the anterior portion of the lens, the locationof the posterior portion of the lens and the location of the retina. Ina preferred embodiment, the operating sequence includes each of awavefront aberrometry measurement, a corneal topography measurement andan OCT scan, wherein the OCT scan is taken at least at the retina, thecornea and one of anterior portion of the patient's lens. Preferably, aniris image is taken simultaneously with or sequentially with an each ofmeasurements taken with wavefront aberrometry subsystem the CornealTopography Subsystem and the OCT subsystem, including an iris image takesimultaneously with or sequentially with the location of each OCT scan.This results in improved accuracy in the 3-dimensional modeling of thepatient's eye by permitting the various data sets to be fused and mergedinto a 3-dimensional model.

FIG. 8 shows one embodiment of an operating sequence and method in whichwavefront aberrometry measurements, corneal topography measurements andOCT measurements are all taken. The optical measurement apparatus,including the method of FIG. 8 may be used preoperatively,intra-operatively and/or postoperatively. In the method of FIG. 8, astep 501 comprises aligning the optical measurement system to the eye ofthe patent. A step 505 comprises activating the Target Fixationsubsystem for patient fixation on target. A step 510 comprisesactivating the wavefront aberrometer subsystem such that the wavefrontaberrometer light source 510 is activated and the eye refraction ismeasured via the wavefront sensor. A step 515 comprises activating thetarget fixation system to move the target to an optimum position andactivate the wavefront aberrometer subsystem such that the wavefrontaberrometer light source 152 is activated and the eye refraction ismeasured via the wavefront sensor 155. A step 520 comprises obtaining aniris image using Iris Imaging Subsystem while infrared light source 152is operating. A step 525 comprises operating the z-scan device to setOCT scan location at or near cornea, and performing an OCT Scan with theOCT Subsystem. A step 530 comprises operating the z-scan device to setthe OCT location at a location at or near the lens anterior andperforming an OCT Scan with the OCT Subsystem. A step 535 comprisesoperating the z-scan device to set the OCT location at a location at ornear the lens posterior and performing an OCT Scan with the OCTSubsystem. A step 540 comprises operating the X-scan device and Y-scandevice so no light from OCT reaches detector 141. A step 545 comprisesobtaining an iris image using the Iris Imaging Subsystem while theinfrared light source 152 flashes. A step 550 comprises obtaining aniris image using the Iris Imaging Subsystem while the light sources 120and helmholz source flash. A step 550 comprises measuring the cornealtopography with the Corneal Topography Subsystem. A step 555 comprisesoperating the z-scan device to set the OCT location at a location at ornear the retina and performing an OCT Scan with the OCT Subsystem. Astep 560 comprises operating the X-scan device and Y-scan device so nolight from OCT reaches detector 141. An optional step 565 comprisesmeasure corneal topography with Corneal Topography Subsystem, which mayprovide for an improved 3D model of the patient eye. An optional step570 comprises obtaining an iris image using Iris Imaging Subsystem (for3D model).

FIG. 9 shows one embodiment of an operating sequence and method in whichno wavefront aberrometry measurements are taken. The optical measurementapparatus, including the method of FIG. 8 may be used preoperatively,intra-operatively and/or postoperatively. In the embodiment of FIG. 9, astep 601 comprises aligning the optical measurement system to the eye ofthe patent. A step 605 comprises activating the Target Fixationsubsystem for patient fixation on target. A step 610 comprises obtainingan iris image using Iris Imaging Subsystem while infrared light source152 is operating. A step 615 comprises operating the z-scan device toset OCT scan location at or near cornea, and performing an OCT Scan withthe OCT Subsystem. A step 620 comprises operating the z-scan device toset the OCT location at a location at or near the lens anterior andperforming an OCT Scan with the OCT Subsystem. A step 625 comprisesoperating z-scan device to set the OCT location at a location at or nearthe lens posterior and performing an OCT Scan with the OCT Subsystem. Astep 530 comprises operating the X-scan device and Y-scan device so nolight from OCT reaches detector 141. A step 635 comprises obtaining aniris image using the Iris Imaging Subsystem while the infrared lightsource 152 flashes. A step 640 comprises measuring the cornealtopography with the Corneal Topography Subsystem. A step 645 comprisesoperating the z-scan device to set the OCT location at a location at ornear the retina and performing an OCT Scan with the OCT Subsystem. Astep 650 comprises operating the X-scan device and Y-scan device so nolight from OCT reaches detector 141. An optional step 655 comprisesmeasuring corneal topography with Corneal Topography Subsystem, whichmay provide for an improved 3D model of the patient eye. An optionalstep 660 comprises obtaining an iris image using Iris Imaging Subsystem.

FIG. 10 shows an embodiment of an operational sequence and method inwhich OCT measurements utilizing the OCT subsystem and Iris images usingthe iris imaging subsystem may be taken simultaneously in order toimprove three dimensional modeling of the patient's eye and improvediris registration of the measurement data sets. The operational sequenceof FIG. 10 may be applied to or incorporated into either of theoperational sequences and methods of FIG. 8 or 9 as would be readilyunderstood by those ordinarily skilled. In order to effectuate theoperating sequence and method of FIG. 10, a lens is inserted intooptical path 170 between beam splitter 173 and detector 141. Theinserted lens is selected to preferentially pass infrared light used foriris imaging but to block an OCT beam from the OCT light source fromreaching detector 141. In this configuration, OCT measurements and irisimages may be taken simultaneously. Further, in the embodiment of FIG.10 a regular speed global shutter iris camera is used operating at 12frames/second. The operating sequence and method of FIG. 10 may be usedpreoperatively, intra-operatively and/or postoperatively.

In the embodiment of FIG. 10, a step 701 comprises aligning the opticalmeasurement system to the eye of the patent. A step 705 comprisesactivating the Target Fixation subsystem for patient fixation on target.A step 710 comprises obtaining an iris image using Iris ImagingSubsystem while infrared light source 152 is operating. A step 715comprises obtaining an iris image using Iris Imaging Subsystem whilecorneal topography light sources 120 and Helmholz light source 132 areoperating. A step 720 comprises operating the z-scan device to set OCTscan location at or near cornea, and performing an OCT Scan with the OCTSubsystem. A step 725 comprises operating the z-scan device to set theOCT location at a location at or near the lens anterior and performingan OCT Scan with the OCT Subsystem. A step 730 comprises operatingz-scan device to set the OCT location at a location at or near the lensposterior and performing an OCT Scan with the OCT Subsystem. A step 735comprises obtaining an iris image using Iris Imaging Subsystem whileinfrared light source 152 is operating. A step 740 comprises obtainingan iris image using Iris Imaging Subsystem while corneal topographylight sources 120 and Helmholz light source 132 are operating. A step745 comprises operating the z-scan device to set the OCT location at alocation at or near the retina and performing an OCT Scan with the OCTSubsystem. A step 750 comprises obtaining an iris image using IrisImaging Subsystem while corneal topography light sources 120 andHelmholz light source 132 are operating. A step 755 comprises obtainingan iris image using Iris Imaging Subsystem while infrared light source152 is operating.

FIG. 11 shows another embodiment of an operational sequence and methodin which OCT measurements utilizing the OCT subsystem and Iris imagesusing the iris imaging subsystem may be taken simultaneously in order toimprove three dimensional modeling of the patient's eye and improvediris registration of the measurement data sets. The operational sequenceof this embodiment may be applied to or incorporated into either of theoperational sequence and methods of FIG. 8 or 9 as would be readilyunderstood by those ordinarily skilled. As with the method of FIG. 10,in order to effectuate the operating sequence and method of FIG. 11, alens is inserted into optical path 170 between beam splitter 173 anddetector 141. The inserted lens is selected to preferentially passinfrared light used for iris imaging but to block an OCT beam from theOCT light source from reaching detector 141. In this configuration, OCTmeasurements and iris images may be taken simultaneously. Further, inthe embodiment of FIG. 10 a high speed global shutter iris camera, orfast frame rate, is used operating at 60 frames/second. Under the fastframe rate conditions of this embodiment, an infrared illuminationsource, such as a wavefront aberrometry source, may be used with a oneor more second light sources, such as a combination of the cornealtopography sources 120 and the Helmholz source, to alternatelyilluminate a patient's eye repeatedly at short intervals (i.e.,alternative short flashes). Under these conditions, the iris imagingsubsystem may be synched to the flash from each source so as to captureiris images under both illumination conditions. The operating sequenceand method of FIG. 11 may be used preoperatively, intra-operativelyand/or postoperatively.

In the embodiment of FIG. 11, a step 801 comprises aligning the opticalmeasurement system to the eye of the patient. A step 805 comprisesactivating the Target Fixation subsystem for patient fixation on target.A step 810 comprises obtaining an iris image using Iris ImagingSubsystem while infrared light source 152 is operating and obtaining aniris image using Iris Imaging Subsystem while corneal topography lightsources 120 and Helmholz light source 132 are operating. This is done byalternately operating the infrared light source and a combination of thecorneal topography/Helmholz light sources so as to alternatelyilluminate the patient's eye with the infrared light source and thecombined light sources, preferably at a rate that a patient's eye cannotresolve the “flicker.” In this step, the Iris imaging subsystem is insynch with the respective illuminate lights. A step 815 comprisesoperating the z-scan device to set OCT scan location at or near cornea,and performing an OCT Scan with the OCT Subsystem. A step 820 comprisesoperating the z-scan device to set the OCT location at a location at ornear the lens anterior and performing an OCT Scan with the OCTSubsystem. A step 825 comprises operating z-scan device to set the OCTlocation at a location at or near the lens posterior and performing anOCT Scan with the OCT Subsystem. A step 830 comprises operating thez-scan device to set the OCT location at a location at or near theretina and performing an OCT Scan with the OCT Subsystem. A step 835comprises obtaining an iris image using Iris Imaging Subsystem whileinfrared light source 152 is operating and obtaining an iris image usingIris Imaging Subsystem while corneal topography light sources 120 andHelmholz light source 132 are operating as described above for Step 810.

Placido style-based or spot-based topographers work by shining a patternof light on the eye. If a patient is looking directly into aninstrument, there is often a portion of the cornea that is notilluminated because of a shadow created by the patient's nose. Onesolution employed by some topographers is to have the patient look intothe instrument with about a degree angle. This simply moves the noserelative to the instrument so there is no shadow on the cornea. To aidin orienting the patients head properly, the chin rest often has two tendegree indentations, one for the left eye and the other for the righteye. This solution works well for an instrument that is dedicated toonly measuring corneal topography. But it has drawbacks with aninstrument that is meant to measure more characteristics of the eye suchas refractive state, gaze angle, angle kappa and iris features. In anintegrated system that includes a corneal topographer and an OCT system,it is advantageous to combine the results from both into a singledisplay map of corneal topography. In the region where the topographerimage is illuminated, the highest accuracy characterization of theoptical surface may be obtained. Then in extended regions where the OCTelevation data is available, that information can be used in the samemap. The combined map may also include an annular zone that extendsbeyond the roughly circular region of corneal topographer coverage,

Several methods may be used to join the OCT data set to the placidostyle spot based topographer data set. One method is to use as areference an image taken with the same camera as the topographer butwith the topographer pattern turned off and simple illumination from oneor a few light sources turned on. Another is to have the scan mirrorsfrom the OCT pause momentarily at certain locations so light from theOCT is bright enough to be seen on the camera. Another is to perform XYpolynomial shape fits on both OCT and topographer data sets and jointhose together in best fit method. In that case the OCT data that iscollected in the same region as the topographer data is being used toassist in performing the match. Another more direct method is simply tohave done a step at a previous point in time, for instance duringmanufacture and calibration, where the relationship between the OCT scanpattern and image locations on the camera have been established. Thismay be done simply by placing a reflective target at the measurementplane and recording images of the scan pattern of the OCT. In theory, inan ideal system the entirety of the OCT beam would be going into the OCTmeasurement optical path, but in practice it is found that a very smallamount of light leakage at the OCT wavelength that reaches the camera issufficient to perform such a calibration.

FIG. 12 is a simplified block diagram illustrating an assembly 100according to another embodiment of the present invention that furthercomprises a posterior corneal astigmatism assembly 900. Except for theinclusion of the posterior corneal astigmatism assembly, the othercomponents may be same as are described with respect to FIGS. 1-11.Specifically, the assembly 100 according to many embodiments includes anthe optical coherence tomographer (OCT) subsystem 190, the wavefrontaberrometer subsystem 150, the corneal topographer subsystem 140 formeasuring one or more characteristics of a subject's eye, an irisimaging subsystem 40, the fixation target subsystem 180 and the sharedoptics 50 as described above with respect to FIGS. 1-11.

The posterior corneal astigmatism assembly 900 generally comprises afirst detector 910 at a first effective optical distance D₁ from apredetermined location anterior or posterior to the patient's cornea anda second detector 920 at a second effective optical distance D₂ from thepredetermined location. In many embodiments, the effective opticaldistance D₁ is less than the effective optical distance D₂. In theseembodiments, the first detector 910 is referred to as the near detectorand the second detector 920 is referred to as the far detector. Thefirst and second detectors 910, 920 are generally detectors suitable fordetecting visible and/or infrared light, such as a CCD, and morespecifically capable of detecting light reflected from the patient'seye.

Without being limited to theory, the posterior corneal astigmatismassembly 900 is based on the principle that the amount of distortion ofan object by a toric lens that is detected by a detector depends on adistance of the detector from the toric lens. More specifically, theamount of detected distortion increases with increasing distance fromthe toric lens. For example, when a toric spectacle lens is placed infront of a patient's eye, it introduces distortion into the image thepatient perceives. Because of the action of the toric lens in theseinstances, a patient may perceive a physically round object as adistorted oval with the axis of the oval pointing along the axis of theastigmatism. Further, the closer the lens is to the eye, the lessdistortion the patient perceives. For instance, a toric contact lens ona patient's eye may cause almost no perceivable distortion. FIG. 13Aillustrates an image detected of a round object by a detector with atoric lens disposed between the round object and the detector when thedetector is near the toric lens. FIG. 13B illustrates an image detectedof a round object by a detector with a toric lens disposed between theround object and the detector when the detector is further from thetoric lens.

The same principle can be applied to the situation where the corneaitself replaces the toric lens in the preceding example. In brief, thetotal astigmatism and the posterior corneal astigmatism of the patient'seye are obtained by measuring the effect of the cornea on lightreflected from one or more structures posterior to the cornea within thepatient's eye. In accordance with many embodiments, two detectors 910,920 located at different effective optical distances D₁, D₂ from theeye, obtain simultaneous images of a predetermined structural featureposterior to the cornea within the patient's eye. Optical elements 904,902, preferably beam splitters, deflect light from the optical axis 102to the near detector 910 and the far detector 920, respectively. Lightreflected from within the eye provides structural information regardinga predetermined structure in the patient's eye, passes through thecornea and is detected by both the near detector 910 and the fardetector 920. The near detector 910 at the shorter effective opticaldistance D₁ from the predetermined structure represents the lessdistorted image of the predetermined structure. In many embodiments, thenear detector may be sufficiently close to the patient's eye that it maybe deemed an undistorted image of the predetermined structure. The fardetector 920 at the longer effective optical distance D₂ ischaracterized has having a greater distorted image of the targetstructure. In connection with the posterior corneal astigmatism assemblyof many embodiments, the amount of distortion at the far detector 920,preferably in comparison to the image from the first detector 910,reveals the total corneal astigmatism of the eye.

The predetermined structure imaged by the near detector 910 and the fardetector 920 is preferably the iris 406, and more preferably, a boundaryof the iris. In principle, the strongest distortion effect would beexpected when the predetermined structure being imaged is at the focuspoint of the cornea. However, the focus point of the cornea (410, FIG.5) is the retina (476, FIG. 5), and the crystalline lens (402, FIG. 5)of the eye is between the cornea and the lens. The presence of the lenssignificantly complicates any attempt to look at retinal features forcorneal distortion analysis. Conversely, the iris of the eye lies inbetween the cornea and the lens, which eliminates the lens as aconfounding factor. As a result, in a preferred embodiment, thepredetermined structure to be imaged is the iris, or more specifically,a boundary thereof. To obtain a clear iris boundary, an infrared lightsource is directed onto the retina. In a preferred embodiment, backscatter from the retina uniformly back illuminates the pupil of the eye,passes the cornea and is detected substantially simultaneously by thenear detector 910 and the far detector 920 to produce iris images at thefirst effective optical distance D₁ and the second effective opticaldistance D₂.

In some embodiments, an effective optical distance is a physicaldistance between a predetermined location anterior to the iris, oranterior to the cornea, and a detector, preferably an entrance pupil ofthe detector. The predetermined location is preferably in a location ator near the apex 407 of the cornea. In some embodiments, thepredetermined location is less than 2 mm from the apex 407 of the corneaor less than 1 mm from the apex of the cornea. Conversely, one or moreoptical elements 901, 902 may be used to optically relay the entrancepoint of the detector to a second predetermined location, for instanceto a predetermined location at or near the apex of the cornea. Whenoptical elements 901, 902 are used to relay a position of a detector,the effective optical distance is a distance between the predeterminedlocation and the relayed position of the detector. The optical relay thedetector's entrance pupil of may be relayed by a telescope, such as a 4Ftelescope, or holographic optical elements.

When clinically feasible, the near detector 910 may be physically placedat or very near to the apex of the cornea of the eye. However, inpractice, this will typically be inconvenient clinically. Instead, it isadvantageous to optically relay the entrance pupil of the near detector910 to near the apex of the cornea by means of a telescope, such as a 4Ftelescope. Holographic optical elements can serve the same purpose.

In some embodiments, the relay of the near detector 910 by, forinstance, the 4F telescope, also makes it possible to position theentrance pupil of the near detector 910 to be a few millimeters withinthe eye, at the eye's exit pupil instead of the corneal apex. This planeis the virtual image of the iris of the eye as seen underneath thecornea. In human eyes, this location varies over a narrow range of lessthan 2 mm. In either case, whether the entrance pupil is relayed to thecorneal apex or iris, the near detector 910, such as a camera, isfocused on the iris feature to obtain the image for the data analysis. Alens 903 may be used to direct the back reflected to the near detector910.

The far detector 920 may generally be placed at any suitable effectiveoptical distance. In many embodiments, a suitable effective opticaldistance for the far detector 920 is between about 50 mm and 500 mm, orbetween about 100 mm and 300 mm or about 100 mm to 200 mm Like the neardetector 910, the far detector 920, such as a camera, is preferablyfocused on the iris when the image is obtained for the data analysis. Insome embodiments, a camera lens 904 with a long zoom may be placedremotely from the eye to direct to the light to the far detector 920.

In some embodiments, images from the near detector 910 and far detector920 are obtained at two or more eye pupil diameters. This can beachieved by changing a target light brightness to control pupildiameter. The near and far detectors can be configured to acquire imagesimultaneously at the different pupil diameters to obtain the best dataset for analysis.

The simultaneous imaging by near detector 910 and far detector 920provides the total corneal astigmatism. To find the posterior cornealastigmatism, the anterior corneal astigmatism is subtracted from thetotal corneal astigmatism. This can be done, for instance, with vectoralmethods to get the axis correct as is known to those ordinarily skilled.The amount of distortion seen by the far detector 920 is proportional tothe distance that the iris is from the apex of the cornea. As such, theaccuracy of the total corneal astigmatism and posterior cornealastigmatism calculations can be improved if an accurately measuredanterior chamber depth is included.

Preferably, the anterior corneal topographer needed to obtain theanterior corneal astigmatism is incorporated into the opticalmeasurement system 1 described herein that includes a cornealtopographer subsystem shown in FIGS. 2, 3A and 3B. However, the anteriorcorneal topography may be performed on a separate instrument and can bebased for instance on a placido style-based or spot-based cornealtopographer.

FIG. 14 shows an alternate arrangement exhibiting the near and fardetectors that can be used to determine the total corneal astigmatism.The near detector 910 is located an effective distance of D1 from theeye. The pair of lenses 901 and 175 together behave as a singleeffective lens so that the effective lens focal length may be calculatedaccording to the well-known “lens maker equation” and the distance fromthe lens 175 to the eye is greater than that effective lens focallength. The distance of the detector 910 from lens 901 is set so thatthe detector is focused on the iris of the eye. In FIG. 14, the detector141 is the far detector. The lenses 175 and 174 are separated by the sumof their focal lengths making them an afocal system. Effectively, thelight patterns received by the camera from the eye is the same as thatobtained from a detector located far away.

FIG. 15 shows the far and near detectors operating as a separate systemfor determining the total corneal astigmatism of a patient's eye. Twocameras view the eye. The dashed lines show rays that indicate theimaging condition. The eye iris 406 eye is imaged through the cornea407. In the presence of astigmatism on the cornea, the imaging conditionmay not be exactly satisfied but the offset from the ideal best focus issmall enough that a clear image of the iris still appears on the camerasensors 1604 and 1605. In practice the spherical power of the cornea isabout 43 diopters and the cylindrical optical power of the cornea istypically about one to two diopters. The beam splitting element 1601sends light into both optical paths. The lens 1603 has a shorter focallength than the lens 1602. So the camera sensor 1605 is considered thenear detector and camera sensor 1604 is the far detector. For thepurpose of illustration, we can consider the case when the iris 406 ofthe eye has a circular shape. Then if the cornea 407 has a low strengthof astigmatism, the image seen on both near and far cameras is circular.But when the cornea has strong astigmatism, the near camera sees asubstantially circular iris as in FIG. 13A while the far camera sees anelliptical pattern as in FIG. 13B. The orientation of the ellipse alsoshows the angle of the astigmatic axis. However, in most eyes, the iris406 inside the eye has a slightly elliptical shape, so it is notpossible to deduce the astigmatism of the eye solely from far cameraimage alone. The comparison of the ellipticity between the image givesthe total corneal astigmatism. Determination of the strength of thecylinder may be accomplished by analyzing the short and long axes of theellipse and applying the thin lens imaging equation to long and shortaxes independently.

FIG. 16 shows the addition of the corneal topographer to the totalcorneal astigmatism system depicted in FIG. 15. The topography data maybe analyzed to give the anterior spherical power and astigmatism of theanterior of the cornea. Simple subtraction of the anterior cylinderpower from the total corneal astigmatism gives the posterior astigmatismpower.

The arrangement of the near detector 910 and far detector 920 also makesit possible to calculate range to an object by comparing object sizes byknown triangulation techniques or by other ray tracing means known tothose ordinarily skilled.

The posterior corneal astigmatism assembly 900 may be used in LASIKsurgery to improve results by accurately measuring posterior cornealastigmatism.

The optical measurement instrument 1 and the optical measurementsobtained therewith may be used pre-operatively, i.e. before a cataractsurgery or other surgical procedure, for, e.g., eye biometry and othermeasurements, diagnostics and surgical planning Surgical planning mayinclude one or more predictive models. In the one or more predictivemodels, one or more characteristics of the postoperative condition ofthe patient's eye or vision is modeled based on one or more selectedfrom the group consisting of pre-operative measurements obtained fromthe optical measurement instrument 1, a contemplated surgicalintervention, and on or more algorithms or models stored in the memoryof the optical measurement system 1 and executed by the processor. Thecontemplated surgical intervention may include the selection of an IOLfor placement, the selection of an IOL characteristic, the nature ortype of incision to be used during surgery (e.g., relaxation incision),or one or more post-operative vision characteristics requested by thepatient.

The optical measurement instrument 1 and the optical measurementsobtained therewith may be used intra-operatively, i.e., during acataract surgery or other surgical procedure, for, e.g., intraoperativeeye diagnostics, determining IOL position and/or orientation, surgicalplanning, and control/or of a laser surgical system. For instance, inthe case of laser cataract surgical procedure, any measurement dataobtained preoperatively by the optical measurement instrument may betransferred to a memory associated with a cataract laser surgical systemfor use before, during or after either the placement of a capsulotomy,fragmentation or a patient's lens or IOL position and/or orientationduring the cataract surgery. In some embodiments, measurements usingoptical measurement instrument 1 may be taken during the surgicalprocedure to determine whether the IOL is properly placed in thepatient's eye. In this regard, conditions measured during the surgicalprocedure may be compared to a predicted condition of the patient's eyebased on pre-operative measurements, and a difference between thepredicted condition and the actual measured condition may be used toundertake additional or corrective actions during the cataract surgeryor other surgical procedure. The corrective procedure may also be merelybased on intraoperative measurements so that the actual measuredcondition dictates the action that is needed to provide the desiredoutcome.

The optical measurement instrument 1 and the optical measurementsobtained therewith may be used postoperatively, i.e., after a cataractsurgery or other surgical procedure, for, e.g., post-operativemeasurement, postoperative eye diagnostics, postoperative IOL positionand/or orientation determinations, and corrective treatment planning ifnecessary. The postoperative testing may occur sufficiently after thesurgery that the patient's eye has had sufficient time to heal and thepatient's vision has achieved a stable, postsurgical state. Apostoperative condition may be compared to one or more predictedcondition performed pre-operatively, and a difference between thepreoperatively predicted condition and the postoperatively measuredcondition may be used to plan additional or corrective actions duringthe cataract surgery or other surgical procedure. The correctiveprocedure may also be merely based on intraoperative measurements sothat the actual measured condition dictates the action that is needed toprovide the desired outcome.

Instrument 1 stores all the biometric data and postoperative informationin an embedded database, so that the data contained in this database canbe used to further optimize or generate new algorithms to improve futurepatient's outcomes. In certain embodiments, these algorithms are relatedto optimize actual lens position prediction, surgically inducedastigmatism, IOL constants or personalized regressions to account forcorneal spherical aberration in IOL power calculations for post-LASIKeyes.

The optical measurement instrument 1, including the Corneal TopographySubsystem, the OCT subsystem and the wavefront aberrometry subsystem,utilizing a suitable operating sequence as disclosed herein, is operableto measure one, more than one or all of the following: ocular biometryinformation, anterior corneal surface information, posterior cornealsurface information, anterior lens surface information, posterior lenssurface information, lens thickness information, lens tilt informationand lens position information. In some embodiments, the ocular biometryinformation may include a plurality of central corneal thicknesses(CCT), an anterior chamber depth (ACT), a pupil diameter (PD), a whiteto white distance (WTW), a lens thickness (LT), an axial length (AL) anda retinal layer thickness. This measurement data may be stored in memory62 associated with controller 60. The plurality of characteristics maybe measured preoperatively, and where appropriate, intra-operatively,and postoperatively.

In some embodiments, memory 62 associated with controller 60 may storeintraocular lens (IOL) model data for a plurality of IOL models, each ofthe IOL models having associated with it a plurality of predeterminedparameters selected from the group consisting of dioptic power,refractive index and dispersion, asphericity, toricity, echelletefeatures, haptic angulation, and lens filter. The IOL data may be usedby one or more processors of optical measurement instrument 1, inconjunction with measurement data of a subject's eye obtained by opticalmeasurement instrument 1, for cataract diagnostics or cataract treatmentplanning, which may include specifying and/or selecting a particular IOLfor a subject's eye. For example, one or more processors of opticalmeasurement instrument 1 may execute an algorithm which includes:accessing the plurality of IOL models stored in, and for each of the IOLmodels: (1) modeling the subject's eye with an intraocular lenscorresponding to the IOL model and the measured characteristics of thesubject's eye; (2) simulating the subject's eye based on the pluralityof IOL predetermined parameters and the predicted IOL position; (3)performing one of a ray tracing and a power calculation based on saidmodel of the subject's eye; and (4) selecting an IOL for the subject'seye from the plurality of IOL models corresponding to the optimized IOLbased on a predetermined criteria.

In some embodiments, one or more processors of optical measurementinstrument 1 may execute an algorithm comprising: determining a desiredpostoperative condition of the subject's eye; empirically calculating apost-operative condition of the eye based at least partially on themeasured eye characteristics; and predictively estimating, in accordancewith an output of said empirically calculating and the eyecharacteristics, at least one parameter of an intraocular lens forimplantation into the subject's eye to obtain the desired postoperativecondition.

In many embodiments, the eye imaging and measurement system furthercomprises a memory operable to store Intraocular Lens (“IOL”) Data, theIOL data including a plurality of dioptic power, anterior and posteriorradius, IOL thickness, refractive index and dispersion, asphericity,toricity, echelette features, haptic angulation, and lens filter.

In many embodiments, the eye imaging and measurement system furthercomprises a memory operable to store intraocular lens (“IOL”) model datafor a plurality of IOL models, IOL model having associated with aplurality of predetermined parameters selected from the group consistingof dioptic power, anterior and posterior radius, IOL thickness,refractive index and dispersion, asphericity, toricity, echelettefeatures, haptic angulation, and lens filter.

An improved system for selecting an intraocular lens (IOL) forimplantation, comprises: a memory operable to store data acquired fromeach of the Corneal Topography Subsystem, the wavefront sensor subsystemand the Optical Coherence Tomography subsystem, wherein the stored dataincludes a plurality of ocular biometry information, anterior cornealsurface information, posterior corneal surface information, anteriorlens surface information, and posterior lens surface information, lenstilt information, lens thickness information, and lens positioninformation; the memory further operable to store intraocular lens(“IOL”) model data for a plurality of IOL models, IOL model havingassociated with it a plurality of predetermined parameters selected fromthe group consisting of dioptic power, anterior and posterior radius,IOL thickness, refractive index and dispersion, asphericity, toricity,echelette features, haptic angulation, and lens filter; and a processorcoupled to the memory, the processor deriving the treatment of the eyeof the patient applying, for each of the plurality of identified IOLModel, to: (1) predict a position of one of the identified IOL Modelswhen implanted in the subject eye, based on the plurality ofcharacteristics; (2) simulate the subject eye based on the plurality ofIOL predetermined parameters and the predicted IOL position; (3) performone or more of ray tracing and an IOL spherical equivalent (SE) andcylinder (C) power calculation, as well as optionally, to determine theoptimum IOL orientation based on said eye model; and (4) propose one IOLpower for one or more IOL models from the plurality of IOLscorresponding to the optimized IOL(s) based on predetermined criteria;and (5) show the simulated optical quality and/or visual performanceprovided by each of the proposed IOL models for distance and/or for anyother vergence and/or field angle.

A method of selecting an intraocular lens (IOL) to be implanted in asubject's eye, comprising: measuring a plurality of eye characteristicscomprising ocular biometry information, anterior corneal surfaceinformation, posterior corneal surface information, anterior lenssurface information, and posterior lens surface information, lens tiltinformation, lens thickness information and lens position information;and for each of Intraocular Lens (“IOL”) model having associated with ita plurality of predetermined parameters selected from the groupconsisting of dioptic power, refractive index and dispersion, anteriorand posterior radius, IOL thickness, asphericity, toricity, echelettedesign, haptic angulation, and lens filter: (1) modeling the subject eyewith the intraocular lens; (2) simulating the subject eye based on theplurality of IOL predetermined parameters and the predicted IOLposition; (3) performing a ray tracing and an IOL spherical equivalent(SE) and cylinder (C) power calculation, as well as determine theoptimum IOL orientation based on said eye model; and (4) proposing oneIOL power for one or more IOL models from the plurality of IOLscorresponding to the optimized IOL(s) based on predetermined criteria;and optionally (5) show the simulated optical quality and/or visualperformance provided by each of the proposed IOL models for distanceand/or for any other vergence and/or field angle.

A tangible computer-readable storage device storing computerinstructions which, when read by a computer, cause the computer toperform a method comprising: receiving a plurality of eyecharacteristics comprising ocular biometry information, anterior cornealsurface information, posterior corneal surface information, anteriorlens surface information, and posterior lens surface information, lenstilt information, lens thickness information and lens positioninformation; for each of Intraocular Lens (“IOL”) model havingassociated with it a plurality of predetermined parameters selected fromthe group consisting of dioptic power, refractive index and dispersion,anterior and posterior radius, IOL thickness, asphericity, toricity,echelette design, haptic angulation, and lens filter: (1) simulating ageometry of the subject eye with each of the plurality of intraocularlenses (IOL) implanted, in accordance with the plurality of eyecharacteristics; (2) performing a ray tracing and an IOL sphericalequivalent (SE) and cylinder (C) power calculation, as well asoptionally determining the optimum IOL orientation based on said eyemodel; (3) proposing one IOL power for one or more IOL models from theplurality of IOLs corresponding to the optimized IOL(s) based onpredetermined criteria; and optionally (4) showing the simulated opticalquality and/or visual performance provided by each of the proposed IOLmodels for distance and/or for any other vergence and/or field angle.

A method of predicting the intraocular lens position comprising:determining a plurality of eye characteristics before cataract surgery,comprising ocular biometry information, anterior corneal surfaceinformation, posterior corneal surface information, anterior lenssurface information, and posterior lens surface information, lens tiltinformation, lens thickness information and lens position information;determining a plurality of eye characteristics after cataract surgery,comprising ocular biometry information, anterior corneal surfaceinformation, posterior conical surface information, anterior IOL surfaceinformation, and posterior IOL surface information, IOL tiltinformation, and IOL position information; calculating or measuring,based on a mathematical relationship, a distance from the apex or fromthe retina to a plane of the intraocular lens after an ocular surgicalprocedure; calculating an optical power of the intraocular lens suitablefor providing a predetermined refractive outcome; wherein a mathematicalrelationship is found between the preoperative and postoperative eyecharacteristics that accurately predict the measured distance from theapex or from the retina to the plane where the intraocular lens is. In acertain embodiment, the method herein described to predict the IOLposition may depend on the IOL model and/or patient's biometricconfigurations.

An improved system for planning a refractive treatment of an eye of apatient, the system comprising: a memory operable to store eyemeasurement data comprising ocular biometry information, anteriorconical surface information, posterior conical surface information,anterior lens surface information, and posterior lens surfaceinformation, lens tilt information and lens position information; aprocessor coupled to the memory, the processor deriving the treatment ofthe eye of the patient applying an effective treatment transferfunction, wherein the effective treatment transfer function is derivedfrom, for each of a plurality of prior eye treatments, a correlationbetween a pre-treatment vector characterizing the eye measurement databefore treatment, and a post-treatment vector characterizingpost-treatment eye measurement data of the associated eye; an outputcoupled to the processor so as to transmit the treatment to facilitateimproving refraction and/or higher order aberration and/or opticalquality of the eye of the patient for one or more multiple vergencesand/or field angles. The processor preferably comprises tangible mediaembodying machine readable instructions for implementing the derivationof the treatment.

An improved method for planning a refractive treatment of an eye of apatient, the system comprises: measuring a plurality of ocular biometryinformation, anterior corneal surface information, posterior cornealsurface information, anterior lens surface information, and posteriorlens surface information, lens tilt information, lens thicknessinformation and lens position information.

A method of customizing at least one parameter of an intraocular lens,comprising: measuring a plurality of eye characteristics comprisingocular biometry information, anterior corneal surface information,posterior corneal surface information, anterior lens surfaceinformation, and posterior lens surface information, lens tiltinformation and lens position information; determining a desiredpostoperative condition of the eye; empirically calculating apost-operative condition of the eye based at least partially on themeasured eye characteristics; and predictively estimating, in accordancewith an output of said empirically calculating and the eyecharacteristics, the at least one parameter of the intraocular lens toobtain the desired postoperative condition.

A method of adjusting the refractive refraction in an eye of a patientwho has undergone cataract surgery comprising: measuring a plurality ofpost-operative eye characteristics in an eye of a patient who haspreviously undergone cataract surgery, the eye characteristicscomprising ocular biometry information, anterior corneal surfaceinformation, posterior corneal surface information, anterior lenssurface information, and posterior lens surface information, lens tiltinformation and lens position information; identifying a plurality ofcorrective procedure based at least partially on one of (1) a comparisonof at least one measured pre-operative eye characteristic and thecorresponding measured post-operative eye characteristic; and (2) acomparison of at least one predicted post-operative eye characteristicand the corresponding measured post-operative eye characteristic; foreach of a plurality of corrective procedures: modeling the subject eyewith the corrective procedure; modeling the subject eye based on thecorrective procedure; performing one of a ray tracing and a powercalculation based on said eye model; and selecting a correctiveprocedure from the plurality of IOL models and/or orientationscorresponding to the optimized IOL model and/or orientation based on apredetermined criteria. In certain embodiments, the adjustment is merelybased on postoperative measurements so that the actual measuredcondition dictates the action that is needed to improve the refractionof the patient.

In some embodiments, the system further comprises a processor configuredto execute an algorithm. The algorithm comprises, for each of the IOLmodels: (1) modeling the subject's eye with an intraocular lenscorresponding to the IOL model and the measured characteristics of thesubject's eye; (2) simulating the subject's eye based on the pluralityof IOL predetermined parameters and the predicted IOL position; (3)performing one of a ray tracing and a power calculation based on saidmodel of the subject's eye; and (4) selecting an IOL from the pluralityof IOL models corresponding to the optimized IOL based on apredetermined criteria.

This summary and the following detailed description are merelyexemplary, illustrative, and explanatory, and are not intended to limit,but to provide further explanation of the invention as claimed.Additional features and advantages of the invention will be set forth inthe descriptions that follow, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription, claims and the appended drawings.

In another embodiment, the systems and methods of the present includemethods of determining an intraocular lens as described in U.S. Pat. No.8,696,120, entitled “System and Methods for Determining Intraocular LensPower,” the entire contents of which are incorporated herein byreference. As described in U.S. Pat. No. 8,696,120, a number of ocularparameters are used in deriving an appropriate lens power forimplantation into the eye. These parameters include axial length (AL),corneal radius (CR) or power (K), and anterior chamber depth prior tosurgery (ACDpre), among others. In general, one or more of theseparameters are used to provide the preoperative estimation of thepostoperative effective lens position (ELP), which is related to theIOL's principal plane, although it may be modified depending on thesurgeon through the optimization of the corresponding IOL constant. TheELP is then used in combination with one or more of these sameparameters to provide an estimate of the correct lens power to provide adesired refractive outcome (typically emmetropia). As shown in U.S. Pat.No. 8,696,120, the combined measurements of VLpre, ACDpre, and LT arehighly predictive in calculating the postoperative vitreous length, fromwhich the position of an implanted intraocular lens or optic can bederived if its thickness is known. The calculated position of optic willgenerally be given in this embodiment in terms of the “postoperativevitreous length” (VLpost), which is defined herein as the distance fromthe back of the IOL to the retina.

In certain embodiments, a highly predictive formulation of VLpost iscalculated based on the following mathematical relationship whichincludes VLpre, ACDpre, and LT:

VL post=C1+C2*VL pre+C3*ACD pre+C4*LT,  (1)

where VLpre is the preoperative vitreous length of the eye measured asthe difference between the AL and the ACDpre plus LT. ACDpre is theanterior chamber depth prior to an ocular surgical procedure as measuredfrom the anterior corneal surface to the anterior lens surface, LT isthe lens thickness, and C1-C4 are constants, that may depend on the IOLmodel. AL, ACDpre and LT may be measured with, for example the AC Masteror other biometer and VLpre can be then be calculated from thesemeasurements.

By way of non-limiting example, in certain 3 piece intraocular lensembodiments, constants for VLpost may be as follows: C1=−0.901;C2=0.982; C3=0.309; and C4=0.545.

In some embodiments, AL may be used rather than VL_(pre) according tothe following mathematical relationship: VL_(post)=AL−(ACD_(pre)+0.5LT). AL may be measured, for example, with the IOL Master. Thisillustrated embodiment was found to be highly predictive of VL_(post)with r²=0.86.

Another embodiment uses AL rather than VL_(pre) according to thefollowing mathematical relationship:VL_(post)=C1+C2*AL+C3*ACD_(pre)+C4*LT where constants in certain 1 pieceintraocular lens embodiments may be as follows: C1=−2.042; C2=0.944;C3=0.396; and C4=0.203. This illustrated embodiment was found to behighly predictive of VL_(post) with r²=0.93. By way of non-limitingexample, in certain 3 piece intraocular lens embodiments, constants forVL_(post) may be as follows: C1=−0.902; C2=0.983; C3=0.673; andC4=0.437. This illustrated embodiment was also found to be highlypredictive of VL_(post) with r²=0.98.

In some embodiments, one or more of the measured variables may be leftout. For example, the measurement of ACD_(pre) may be left out and thecoefficients for LT and VL_(pre) may be evaluated according to thefollowing mathematical relationship: VL_(post)=−C1+C2*VL_(pre)+C3*LTwhere C1=1.63, C2=0.912, and C3=0.448. This illustrated embodiment wasalso found to be highly predictive of VL_(post) with r²=0.86.

Expanding further on this by leaving out LT, the coefficients forVL_(pre) may be evaluated according to the following mathematicalrelationship: VL_(post)=C1+C2*VL_(pre) where C1=4.734 and C2=0.842. Thisillustrated embodiment was also found to be highly predictive ofVL_(post) with r²=0.83. The preoperative vitreous length was found to bea good predictor for the postoperative total power of the eye withr²=0.71.

The systems and methods of the present invention may also incorporate acustomized intraocular lens calculation such as is disclosed in U.S.Pat. No. 8,746,882, entitled “Customized Intraocular Lens PowerCalculation System and Method,” which is incorporated herein in itsentirety. This embodiment generally includes measuring anterior andposterior corneal topography, an axial length (AXL), and an anteriorchamber depth (ACD) of a subject eye, and for each of a plurality ofintraocular lenses (IOLs), simulating the subject eye with theintraocular lens (IOL) implanted in accordance with the measuring,performing either monochromatic or polychromatic ray tracing through thesurfaces defining the built eye model, calculating from the ray tracinga modulation transfer function (MTF)-based value, and selecting the IOLcorresponding to a highest one of the MTF value for implanting in thesubject eye. As used in this embodiment, the modulation transferfunction (MTF) is one measurement of the quality of the system composedby the eye and the implanted IOL power. This function shows how anoptical system transfers the frequency content from the object to theimage. The higher the MTF value, the better the optical system. Thisfunction is closely related to contrast sensitivity measurements, and isalso related to visual acuity when maximum contrast is considered. Ahuman eye with excellent acuity can resolve about 30 sinusoidal cyclesof black and white areas per degree, expressed in cycles per degree(cpd). Alternatively, MTF may be related to spatial frequency in termsof sinusoidal cycles of black and white areas distinguishable permillimeter, expressed as cycles per millimeter (cpmm), for example, 25,50, or 100 cpmm Spatial frequencies like 25 cpmm are especiallyinteresting in vision, because the peak of contrast sensitivity relatedto the visual system is in this region. In this embodiment, the raytracing may be performed polychromatically or monochromatically,depending on the IOL material, at a suitable entrance pupil, such as ator at about a 4 mm entrance pupil, for example. Further, thepolychromatic ray tracing may be performed at about six (6) wavelengthsweighted according the spectral sensitivity curve in photonic or mesopicconditions, although other suitable numbers of wavelengths may be usedaccording to the present invention. calculating of the radially averagedpolychromatic modulation transfer function (RpMTF) (or its monochromaticversion (RMTF) if a monochromatic ray tracing is performed) value may bewith regard to a single optical resolution, herein referred to as “pointvalues,” such as with respect to calculation of the RpMTF/RMTF at or atabout 25 cpmm. Alternatively, Calculating from the ray tracing of theRpMTF/RMTF value may comprise calculating the area under a RpMTF/RMTFcurve, wherein each curve pertains to the RpMTF/RMTF at a plurality ofoptical resolutions. Those skilled in the art will recognize that MTFVolume, Visual Strehl ratio or other suitable optical metrics forpredicting the optical quality for each individual IOL model in thecustomized eye model may be used.

In this embodiment, the system and method may further include measuringa plurality of characteristics of a subject eye, and, with respect to atleast one characteristic for each of a plurality of identified IOLs,predicting a position of the identified IOL when implanted in thesubject eye, simulating the subject eye based on the plurality ofcharacteristics, perform a ray tracing based on the customized eyemodel, calculating from the ray tracing a point from the RpMTF/RMTFvalue, and comparing a plurality of RpMTF/RMTF values corresponding tothe plurality of considered IOLs to identify a highest one of RpMTF/RMTFvalues. Further, the method preferably including identifying one IOLfrom the plurality of IOLs corresponding to the highest one ofRpMTF/RMTF values, and may include outputting the identified one of theIOLs.

Other systems and method that may be used in connection with the presentinvention include the following, all of which are incorporated herein byreference in their entirety: U.S. Pat. No. 8,696,119, entitled “Systemsand Method for Determining Intraocular Lens Power”; U.S. Patent Publ.No. 20014/0253877, entitled, “Intraocular Lens that Matches an ImageSurface to a Retinal Shape and Method of Designing Same”; U.S. PatentPubl. No. 2013/0335701, entitled “Lenses, Systems and Method forProviding Custom Aberration Treatments and Monovision to CorrectPresbyobpia”; U.S. Pat. No. 8,623,081, entitled “Apparatus, System andMethod of Intraocular Lens Power Calculation Using a Regression FormulaIncorporate Corneal Spherical Aberration”; U.S. Patent Publ. No.2013/08282116, entitled “Apparatus, System and Method to Account forSpherical Aberration at the Iris Plane in the Design of an IntraocularLens”; U.S. Patent Publ. No. 2013/0226294, entitled “Apparatus, Systemand Methods for Optimizing Peripheral Vision”; WO 2013/028992, entitled“Ophthalmic Devices, Systems and Method for Optimizing PeripheralVision”; U.S. Pat. No. 8,430,508, entitled “Single Microstructure Lens,Systems And Methods,”; U.S. Pat. No. 8,848,0228, entitled “LimitedEchelette Lens, Systems And Methods”; and U.S. Pat. No. 8,444,267,entitled, “Ophthalmic Lens, Systems And Methods Having At Least OneRotationally Asymmetric Diffractive Structure.

All other patents and patent applications cited here are herebyincorporated by reference hereby reference in their entirety. Also, U.S.Patent Publication No. 2009/0161090, entitled “Systems and Methods forMeasuring the Shape and Location of an Object,” is hereby incorporatedby reference in its entirety.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated here or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. The term “connected” is to beconstrued as partly or wholly contained within, attached to, or joinedtogether, even if there is something intervening. Recitation of rangesof values here are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described here can be performed in any suitableorder unless otherwise indicated here or otherwise clearly contradictedby context. The use of any and all examples, or exemplary language(e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the invention, and does not pose a limitationon the scope of the invention unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the invention.

While certain illustrated embodiments of this disclosure have been shownand described in an exemplary form with a certain degree ofparticularity, those skilled in the art will understand that theembodiments are provided by way of example only, and that variousvariations can be made and remain within the concept without departingfrom the spirit or scope of the invention. Such variations would becomeclear to one of ordinary skill in the art after inspection of thespecification, drawings and claims herein. Thus, it is intended thatthis disclosure cover all modifications, alternative constructions,changes, substitutions, variations, as well as the combinations andarrangements of parts, structures, and steps that come within the spiritand scope of the invention as generally expressed by the followingclaims and their equivalents.

We claim:
 1. An eye imaging and measurement system for planning acataract treatment in a patient's eye, the system comprising: a CornealTopography Subsystem; a wavefront aberrometer subsystem; and an eyestructure imaging subsystem, wherein the subsystems have a sharedoptical axis, and each subsystem is operatively coupled to the othersubsystems via a controller.
 2. The eye imaging and measurement systemaccording to claim 1, wherein the eye structure imaging subsystem isselected from the group consisting of an optical coherence tomographer,a Scheimpflug Imager, a fluorescence imager, a structured lightingimager, a wavefront tomographer, and an ultrasound imager.
 3. The eyeimaging and measurement system according to claim 1, wherein the eyestructure imaging subsystem is a fourier domain optical coherencetomographer.
 4. The eye imaging and measurement device according toclaim 3, wherein the optical coherence tomographer (OCT) is a sweptsource OCT.
 5. The eye imaging and measurement device according to claim1, further comprising a an iris imaging subsystem operatively coupled tothe controller.
 6. The eye imaging and measurement device according toclaim 1, further comprising a fixation target subsystem operativelycoupled to the controller.
 7. The eye imaging and measurement deviceaccording to claim 1, wherein the controller is configured tosequentially scan the eye in a plurality of OCT scan patterns, each scanpattern being at a different axial depth of a patient's eye.
 8. The eyeimaging and measurement device according to claim 7, wherein theplurality of scan patterns comprise an anterior segment OCT scan patternat or near a location of a cornea of the patient, a lenticular OCT scanpattern at or near a location of a lens, and a retinal OCT scan patterat or near a location of a retina.
 9. The imaging and measurement deviceaccording to claim 8, wherein the plurality of imaging scan patternscomprise an anterior segment OCT scan pattern suitable to measure aplurality of an anterior corneal surface, a corneal pachymetry, acentral corneal thickness, and anterior chamber depth of a patient'seye.
 10. The imaging and measurement device according to claim 8,wherein the plurality of imaging scan patterns comprises a lenticularOCT scan segment scan pattern suitable to measure a plurality of a lensthickness, an anterior lens surface, a posterior lens surface, a lenssurface tilt and decentration, IOL surface, IOL position and IOLorientation.
 11. The imaging and measurement device according to claim8, wherein the plurality of imaging scan patterns comprise an retinalOCT segment scan pattern suitable to measure at least one of an axiallength and retinal layer thickness information.
 12. The imaging andmeasurement device according to claim 8, wherein the plurality ofimaging scan patterns comprise an anterior segment scan pattern, alenticular segment scan pattern and a retinal segment scan pattern. 13.The system of claim 1, further comprising a memory operable to storedata acquired from each of the Corneal Topography Subsystem, thewavefront sensor subsystem and the Optical Coherence Tomographysubsystem, wherein the stored data includes a plurality of ocularbiometry information, anterior conical surface information, posteriorcorneal surface information, anterior lens surface information, andposterior lens surface information, lens tilt information and lensposition information.
 14. The system of claim 13, wherein the ocularbiometry information comprises a plurality of central corneal thickness(CCT), anterior chamber depth (ACD), pupil diameter (PD), white to whitedistance (WTW), lens thickness (LT), axial length (AXL) and retinallayer thickness.
 15. The system of claim 1, further comprising a memoryoperable to store Intraocular Lens (“IOL”) Data, the IOL data includinga plurality of dioptic power, anterior and posterior radius, IOLthickness, refractive index and dispersion, asphericity, toricity,echelette features, haptic angulation, and lens filter.
 16. The systemof claim 1, further comprising a memory operable to store intraocularlens (“IOL”) model data for a plurality of IOL models, IOL model havingassociated with a plurality of predetermined parameters selected fromthe group consisting of dioptic power, anterior and posterior radius,IOL thickness, refractive index and dispersion, asphericity, toricity,echelette features, haptic angulation, and lens filter.
 17. A system forselecting an intraocular lens (IOL) for implantation, comprising: amemory operable to store data acquired from each of the CornealTopography Subsystem, the wavefront sensor subsystem and the OpticalCoherence Tomography subsystem, wherein the stored data includes aplurality of ocular biometry information, anterior conical surfaceinformation, posterior corneal surface information, anterior lenssurface information, and posterior lens surface information, lens tiltinformation, lens thickness and lens position information; the memoryfurther operable to store intraocular lens (“IOL”) model data for aplurality of IOL models, IOL model having associated with it a pluralityof predetermined parameters selected from the group consisting ofdioptic power, anterior and posterior radius, IOL thickness, refractiveindex and dispersion, asphericity, toricity, echelette features, hapticangulation, and lens filter; and a processor coupled to the memory, theprocessor deriving the treatment of the eye of the patient applying, foreach of the plurality of identified IOL Model, to: (1) predict aposition of one of the identified IOL Models when implanted in thesubject eye, based on the plurality of characteristics; (2) simulate thesubject eye based on the plurality of IOL predetermined parameters andthe predicted IOL position; (3) perform ray tracing and an IOL sphericalequivalent (SE) and cylinder (C) power calculation, as well as determinethe optimum IOL orientation based on said eye model; and (4) propose oneIOL power for one or more IOL models from the plurality of IOLscorresponding to the optimized IOL(s) based on predetermined criteria;and (5) show the simulated optical quality and/or visual performanceprovided by each of the proposed IOL models for distance and/or for anyother vergence and/or field angle.
 18. A method of selecting anintraocular lens (IOL) to be implanted in a subject eye, comprising:measuring a plurality of eye characteristics comprising ocular biometryinformation, anterior corneal surface information, posterior cornealsurface information, anterior lens surface information, and posteriorlens surface information, lens tilt information, lens thicknessinformation and lens position information; and for each of IntraocularLens (“IOL”) model having associated with it a plurality ofpredetermined parameters selected from the group consisting of diopticpower, refractive index and dispersion, anterior and posterior radius,IOL thickness, asphericity, toricity, echelette design, hapticangulation, and lens filter: (1) modeling the subject eye with theintraocular lens; (2) simulating the subject eye based on the pluralityof IOL predetermined parameters and the predicted IOL position; (3)perform a ray tracing and an IOL spherical equivalent (SE) and cylinder(C) power calculation, as well as determine the optimum IOL orientationbased on said eye model; and (4) propose one IOL power for one or moreIOL models from the plurality of IOLs corresponding to the optimizedIOL(s) based on predetermined criteria; and (5) show the simulatedoptical quality and/or visual performance provided by each of theproposed IOL models for distance and/or for any other vergence and/orfield angle.
 19. A tangible computer-readable storage device storingcomputer instructions which, when read by a computer, cause the computerto perform a method comprising: receiving a plurality of eyecharacteristics comprising ocular biometry information, anterior cornealsurface information, posterior corneal surface information, anteriorlens surface information, and posterior lens surface information, lenstilt information, lens thickness information and lens positioninformation; for each of Intraocular Lens (“IOL”) model havingassociated with it a plurality of predetermined parameters selected fromthe group consisting of dioptic power, refractive index and dispersion,anterior and posterior radius, IOL thickness, asphericity, toricity,echelette design, haptic angulation, and lens filter: (1) simulating ageometry of the subject eye with each of the plurality of intraocularlenses (IOL) implanted, in accordance with the plurality of eyecharacteristics; (2) perform a ray tracing and an IOL sphericalequivalent (SE) and cylinder (C) power calculation, as well as determinethe optimum IOL orientation based on said eye model; and (3) propose oneIOL power for one or more IOL models from the plurality of IOLscorresponding to the optimized IOL(s) based on predetermined criteria;and (4) show the simulated optical quality and/or visual performanceprovided by each of the proposed IOL models for distance and/or for anyother vergence and/or field angle.
 25. A method of predicting theintraocular lens position comprising: providing an eye comprising acornea and a retina; determining a plurality of eye characteristicsbefore cataract surgery, comprising ocular biometry information,anterior corneal surface information, posterior corneal surfaceinformation, anterior lens surface information, and posterior lenssurface information, lens tilt information, lens thickness informationand lens position information; determining a plurality of eyecharacteristics after cataract surgery, comprising ocular biometryinformation, anterior corneal surface information, posterior cornealsurface information, anterior IOL surface information, and posterior IOLsurface information, IOL tilt information and IOL position andorientation information; calculating or measuring, based on amathematical relationship, a distance from the apex or from the retinato a plane of the intraocular lens after an ocular surgical procedure;calculating an optical power of the intraocular lens suitable forproviding at least one of a predetermined refractive outcome and apredetermined optical performance; wherein a mathematical relationshipis found between the preoperative and postoperative eye characteristicsthat accurately predicts the measured distance from the apex or from theretina to the plane where the intraocular lens is.
 20. A system forplanning a refractive treatment of an eye of a patient, the systemcomprising: a memory operable to store eye measurement data comprisingocular biometry information, anterior corneal surface information,posterior corneal surface information, anterior lens surfaceinformation, and posterior lens surface information, lens tiltinformation, lens thickness information and lens position information; aprocessor coupled to the memory, the processor deriving the treatment ofthe eye of the patient applying an effective treatment transferfunction, wherein the effective treatment transfer function is derivedfrom, for each of a plurality of prior eye treatments, a correlationbetween a pre-treatment vector characterizing the eye measurement databefore treatment, and a post-treatment vector characterizingpost-treatment eye measurement data of the associated eye; an outputcoupled to the processor so as to transmit the treatment to facilitateimproving refraction of the eye of the patient.
 21. The system of claim20, wherein the processor comprises tangible media embodying machinereadable instructions for implementing the derivation of the treatment.22. An improved method for planning a refractive treatment of an eye ofa patient, the system comprising: measuring a plurality of ocularbiometry information, anterior corneal surface information, posteriorcorneal surface information, anterior lens surface information, andposterior lens surface information, lens tilt information, lensthickness information and lens position information.
 23. A method ofcustomizing at least one parameter of an intraocular lens, comprising:measuring a plurality of eye characteristics comprising ocular biometryinformation, anterior corneal surface information, posterior cornealsurface information, anterior lens surface information, and posteriorlens surface information, lens tilt information, lens thicknessinformation and lens position information; determining a desiredpostoperative condition of the eye; empirically calculating apost-operative condition of the eye based at least partially on themeasured eye characteristics; and predictively estimating, in accordancewith an output of said empirically calculating and the eyecharacteristics, the at least one parameter of the intraocular lens toobtain the desired postoperative condition.
 24. A method of adjustingthe refraction in an eye of a patient who has undergone cataract surgerycomprising: measuring a plurality of post-operative eye characteristicsin an eye of a patient who has previously undergone cataract surgery,the eye characteristics comprising ocular biometry information, anteriorconical surface information, posterior conical surface information,anterior lens surface information, and posterior lens surfaceinformation, lens tilt information and lens position information;identifying a plurality of corrective procedure based at least partiallyon one of (1) a comparison of at least one measured pre-operative eyecharacteristic and the corresponding measured post-operative eyecharacteristic; and (2) a comparison of at least one predictedpost-operative eye characteristic and the corresponding measuredpost-operative eye characteristic; for each of a plurality of correctiveprocedures: modeling the subject eye with the corrective procedure;modeling the subject eye based on the corrective procedure; performingone of a ray tracing and a power calculation based on said eye model;and selecting a corrective procedure from the plurality of IOL modelscorresponding to the optimized IOL based on a predetermined criteria.25. The eye imaging and measurement system according to claim 1, furthercomprising an posterior corneal astigmatism subsystem.
 26. The eyeimaging and measurement system according to claim 3, wherein the opticalcoherence tomographer comprises a first light source and the wavefrontaberrometer subsystem comprises a second light source different than thefirst light source, and wherein the shared optical axis comprises aquarter wave plate disposed between the first light source and theintended position of an eye of the patient when the patient is properlyaligned with the system and the quarter wave plate is also disposedbetween the second light source and the intended position of the eye.27. The eye imaging and measurement system according to claim 26,wherein the quarter wave plate is a zero order quarter wave plate. 28.The eye imaging and measurement system according to claim 26, whereinthe optical coherence tomographer comprises a reference arm and a samplearm, the sample arm comprises a first polarizer controller for alteringa polarization property of the first light source in the sample arm, andthe reference arm comprises a second polarizer controller for alteringthe polarization property of the first light source in the referencearm.
 29. The eye imaging and measurement system according to claim 28,wherein the first and second polarizer controllers alter thepolarization of the first light source so to be linearly polarized. 30.The eye imaging and measurement system according to claim 29, whereinthe first and second polarizer controllers are a set of polarizationrotating paddle board adjusters.